Monte Rio, CA Real Estate & Homes for Sale
By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.
Monte Rio is an unincorporated river town on the lower Russian River in west Sonoma County, California, made up of single-family homes on the river flat and the slopes above it, many of them second homes or rentals. Redfin put the median sale price at $475,000 for the three months ending August 2026, a little over half the county median. Sonoma County, not a city, sets the rules here, and the river sets most of the due diligence.
- County
- Sonoma County
- Government
- Unincorporated (Permit Sonoma)
- ZIP code
- 95462
- Median sale price
- $475,000 (3 months to Aug 2026, Redfin)
- Water
- Sweetwater Springs Water District
- Flood stage
- 32 ft at the Guerneville river gauge (NWS)
Monte Rio homes for sale
Current MLS listings in Monte Rio appear below. Inventory is small, so most buyers also watch Guerneville, Duncans Mills and Cazadero; our property search covers all of the lower river.
What do homes in Monte Rio sell for?
$475,000
3 months to August 2026, Redfin
$520,717
September 30, 2026, Zillow (surrounding-area data)
46
3 months to August 2026, Redfin
Monte Rio prices sit well below the county’s: the Sonoma County median was $875,000 in September 2026 (C.A.R.). The town trades in single digits each month, though. Redfin counted four sales in August 2026, the same as a year earlier, so one riverfront house or one hillside fixer can move the median by tens of thousands of dollars. Read the figures as a range, not a price list.
| Measure | Figure | Period and source |
|---|---|---|
| Median sale price, Monte Rio | $475,000 (up 0.5% year over year) | 3 months ending August 2026, Redfin |
| Homes sold | 4 in August 2026 (4 in August 2025) | Redfin |
| Average days on market | 46 (53 a year earlier) | 3 months ending August 2026, Redfin |
| Sale price against list | About 4% below list | Past 12 months, Redfin |
| Zillow Home Value Index | $520,717 (up 0.8%; Zillow notes it shows data for the surrounding area) | September 30, 2026, Zillow |
| Homes for sale | 13 | September 30, 2026, Zillow |
| Owners’ median estimate of value | $652,000 (margin ±$66,600) | 2020–2024 American Community Survey, Census Reporter |
| Sonoma County median, for comparison | $875,000 | September 2026, C.A.R. |
The same Census survey counts 774 housing units in the Monte Rio census area but only about 470 households, both with wide margins. Roughly four homes in ten are nobody’s main residence: seasonal homes, vacation rentals and vacant houses. In the county’s own count, 248 of the 400 parcels in its Monte Rio neighborhood have a single-family home on them. That mix is one reason rental rules and flood history weigh on value here as much as square footage.
Where Monte Rio is and who governs it
Monte Rio sits on Highway 116 between Guerneville, upstream, and Duncans Mills, downstream, where the Bohemian Highway meets the river road. It’s a census-designated place with its own post office ZIP, 95462, but no city government. Permit Sonoma handles zoning, building permits, septic permits and vacation rentals, and only the county’s documentary transfer tax applies at sale: $1.10 per $1,000 of value.
The county’s own planning maps break the area into smaller pieces. Its 2023 vacation-rental review counted a “Monte Rio” neighborhood of 400 parcels, Northwood (165 parcels) and Guernewood Park/Monte Rosa (1,060 parcels) toward Guerneville. Nearby Villa Grande shares Monte Rio’s water district. Those names are worth knowing because different rules can apply to each.
How high does the river get in Monte Rio?
River height is the first thing to settle on any Monte Rio property below the hillsides. The National Weather Service measures the Russian River at its Guerneville gauge, upstream of town, and publishes which Monte Rio streets go under at which reading (NOAA National Water Prediction Service).
| Reading at the Guerneville gauge | What the Weather Service expects in Monte Rio |
|---|---|
| 32 ft (flood stage) | Old Bohemian Highway in Monte Rio expected to flood |
| 33 ft | Willow and Alder Streets flood |
| 37 ft | River Boulevard east of Monte Rio floods |
| 39 ft | Highway 116 closed west of Duncans Mills |
| 41.5 ft | Main intersections flood; Monte Rio Elementary School begins to flood |
| 44 ft | Main business section floods; Highway 116 closed west of Guerneville |
The February 2019 storm took the gauge to 45.38 feet at 10:30 p.m. on February 27, past every line in that table. The county’s after-action report calls it the sixth-highest Russian River crest on record and the highest since 1995, when the river reached 48 feet; afterward, fire departments handed out drinking water to residents in the Monte Rio and Cazadero area (Sonoma County Emergency Management). The flood of record is 49.5 feet, in February 1986. Smaller floods come more often: 41.81 feet on New Year’s Day 2006 and 37.82 feet in January 2017. At a 2019-size crest, the list has Highway 116 shut on both sides of town.
Before you commit to a home on the flat, pull the parcel’s FEMA flood zone from the Flood Map Service Center, ask for the elevation certificate and the house’s flood-claim history, and get a flood insurance quote. Homeowner’s policies don’t cover flooding, and a new National Flood Insurance Program policy typically takes up to 30 days to start (Sonoma County Emergency Management).
Raised homes
If a house on the flat has been lifted onto a taller foundation, ask for the building permit and final inspection for the raise, an elevation certificate taken after the work, and the foundation engineering. Then check what’s still below the flood line: the garage, the septic tank, the electrical panel and the driveway. A seller whose parcel is in a FEMA special flood hazard area must say so on the Natural Hazard Disclosure statement.
Water from Sweetwater Springs, and septic instead of sewer
Monte Rio’s water comes from the Sweetwater Springs Water District, a public district formed in 1988 that also serves Guerneville, Rio Nido and Villa Grande. Its Monte Rio system is separate from the Guerneville one and had 1,197 connections in the district’s 2020 Urban Water Management Plan, which describes the supply as groundwater drawn from the Russian River’s underflow. The same plan lists boil-water notices as part of its flood response if the supply is contaminated (Sweetwater Springs Water District). Hillside parcels outside its lines may rely on a well.
Sewer is the bigger question. The Russian River County Sanitation District, run by Sonoma Water, serves Rio Nido, Guerneville, Guernewood Park and Vacation Beach, and none of Sonoma Water’s sanitation districts covers Monte Rio (Sonoma Water). Plan on a septic system unless the seller can show a sewer connection.
- River setback rules: under the county’s septic program, approved by the Regional Water Board in June 2026, every septic system inside the Russian River’s Advanced Protection Management Program is classed Tier 3, which the county’s Local Agency Management Program describes as “enhanced standards,” a higher standard than its regular Tier 2 rules. Where no other boundary is set, that area is land within 600 feet of the riverbank (Permit Sonoma).
- The pathogen rules: the Regional Water Board’s Russian River pathogen plan, approved by the State Water Board on August 18, 2026 and awaiting final state sign-off, adds basic operating inspections of septic systems across the watershed (North Coast Regional Water Board).
- No inspection at sale: the county doesn’t require one, so order your own: a pumped-tank inspection, the permit record and bedroom count, and the leach field’s distance from the river.
Our guide to wells, septic and rural utilities in Sonoma County covers what each inspection should include.
Can you rent a Monte Rio home to visitors?
Sometimes, and Monte Rio is one of the places the county has looked at hardest. Whole-home rentals of 30 days or less need a county zoning permit, a vacation rental license, a certified vacation rental property manager and a transient occupancy tax account. The county’s TOT is 12%, and operators with more than $350,000 a year in rent also pay a 2% tourism assessment.
In its 2023 rezoning review, Permit Sonoma counted 30 rental permits on the 248 home parcels of its Monte Rio neighborhood, a 12.1% concentration, and staff and the Planning Commission recommended a 5% cap. Northwood (17 permits, 15.3%) got the same recommendation, and Guernewood Park/Monte Rosa was recommended for exclusion (Permit Sonoma). The Board of Supervisors then applied cap and exclusion zones to parcels in the Fifth District under Ordinance 6423 in April 2023.
- Cap zone: a new permit is possible only while the neighborhood is below its cap.
- Exclusion zone: no new applications, and an existing permit expires when the property is sold.
- Operating rules: no more than 12 guests, one on-street parking space, a written evacuation plan, defensible space, and licenses only for individuals or family trusts, one per person.
- ADUs: an accessory dwelling unit can’t be a vacation rental, though it can be leased for 30 days or more.
Check the parcel on the county’s vacation rental map viewer before you count on a seller’s rental income. Our guide to vacation rental rules in Sonoma County walks through the permit steps, and long-term tenants in the unincorporated county have just-cause protection from the first day of a tenancy.
Fire zones, insurance and getting in and out
Flooding gets the attention, but hillside lots carry fire risk too. Look up the parcel on CAL FIRE’s Fire Hazard Severity Zone map: the state-area maps took effect April 1, 2024, and the county’s local-area map is dated February 24, 2025 (Permit Sonoma). Where the map shows High or Very High, AB 38 makes defensible space part of the deal: the seller hands over an inspection report from the past six months, or you both sign an agreement that you’ll do the work within a year of closing.
Get insurance quotes early, for fire and flood separately. The state reported in May 2026 that California’s FAIR Plan, the insurer of last resort, added about 16,000 residential policies in the first quarter, down from 35,000 to 50,000 a quarter between 2024 and September 2025 (California Department of Insurance).
Highway 116 is the main road, east to Guerneville and Forestville and west to Duncans Mills and the coast. Sonoma County Transit Route 20 starts at Monte Rio’s Creekside Park stop, with 11 weekday departures plus one Route 20X, and runs through Guerneville, Forestville and Sebastopol to Santa Rosa (Sonoma County Transit). There’s no SMART train on the river.
Parks and daily life around Monte Rio
The redwood parks are upriver, about three miles north of Guerneville. Armstrong Redwoods State Natural Reserve, at 17000 Armstrong Woods Road in Guerneville, covers 805 acres and includes the Colonel Armstrong Tree, estimated at more than 1,400 years old. Austin Creek State Recreation Area shares its entrance and adds about 20 miles of trails, though State Parks says its camping stays closed because of the 2020 Walbridge Fire (California State Parks).
- Schools: the Monte Rio Union Elementary district runs Monte Rio Elementary, a K–8 school at 20700 Foothill Drive (California Department of Education). Confirm the elementary and high school assignment for a specific address with the district.
- Power: Sonoma Clean Power is the default electricity provider, with PG&E delivering it.
For more trail ideas, see our guide to Sonoma County hiking trails.
Monte Rio compared with nearby areas
| Area | What’s different from Monte Rio |
|---|---|
| Guerneville | On the Russian River County Sanitation District’s sewer; larger market, with a ZIP 95446 median of $557,374 (3 months to June 2026, Redfin) |
| Rio Nido | Mostly R1 zoning, where the county has allowed no new vacation rentals since August 2022; on public sewer and Sweetwater’s Guerneville water system |
| Duncans Mills | Inside the Coastal Zone and a County Historic District; Highway 116 closes west of it at 39 ft on the gauge |
| Cazadero | Inland on Austin Creek; under 2020 Walbridge Fire evacuation orders; one sale in the three months to September 2026 (Redfin) |
How Diamond Real Estate Group helps Monte Rio buyers
A Monte Rio purchase turns on facts a listing rarely shows. Before you remove contingencies, we help you pin down three river levels for the property: when water reaches the lot, when it reaches the living floor and when it closes your road. We pull the FEMA zone and elevation certificate, find the septic permit and the tank’s distance from the river, confirm the Sweetwater Springs account, and check the vacation-rental map if rental income is part of the plan.
If the home will be a weekend place, our guide to buying a second home in Sonoma County covers financing and insurance. For the wider picture, see the Sonoma County real estate guide, our step-by-step Sonoma County buying guide and how we work with buyers.
Selling a home in Monte Rio
Monte Rio is unincorporated, so Permit Sonoma is the office for building permits, septic files and vacation rentals. No public sewer district serves the town, which puts the septic system near the top of every buyer’s list.
Septic records to gather
Assemble the septic permit, the system layout and your pumping receipts before the house goes on the market. A system with supplemental treatment needs an operational permit renewed by June 30 each year, plus owner monitoring forms in March and October. Form WLS-043, signed when that system was approved, requires you to notify the next owner of those terms.
Our guide to septic and rural utilities lists what a buyer’s inspector will check.
Raised and riverside homes
- Elevation certificate. Ask Permit Sonoma whether one is on file. If not, hire a civil engineer or licensed land surveyor; the county wants the certificate to show the lowest adjacent grade.
- County elevation grant. A house lifted under the county’s FEMA-funded program carries a recorded deed restriction limiting the space below base flood elevation to storage, a garage or underfloor access. Disclose any rooms built down there.
- Flood insurance. If a past owner took federal disaster aid, FEMA says flood coverage must stay on the structure and a buyer must be told. Many policies can pass to the buyer without a gap.
- Hazard disclosure. The Natural Hazard Disclosure form asks whether the parcel sits in FEMA Zone A or V.
Rental status
The county’s 2023 review recommended a 5% cap for the Monte Rio neighborhood, where permits already covered 12.1% of homes. Permit Sonoma bars new rentals where a cap district is over-concentrated, and only an owner can hold a license, so your buyer needs one of their own. Guernewood Park and Monte Rosa, toward Guerneville, were recommended for exclusion, where an existing permit expires at sale.
Tax and state rules
Only the county documentary transfer tax applies: $0.55 per $500, about $523 on a $475,000 home. The seller customarily pays in Diamond’s North Bay markets, but the split can be negotiated; see how transfer tax works. Hillside lots mapped High or Very High fire hazard need AB 38 paperwork, and every sale needs the smoke alarm, water heater and plumbing fixture disclosures.
Diamond’s seller services begin with these river, septic and permit files.
Sources for this section: Permit Sonoma: Operational Permit and Monitoring Program; Permit Sonoma: Form WLS-043, acknowledgement of operational permit requirement; Permit Sonoma: Floodplains and floodways; County of Sonoma Community Development Commission: Flood Elevation Mitigation Program FAQ; FEMA: Fact sheet, flood insurance: what to know; California Public Law: Civil Code section 1103.2; Permit Sonoma: Vacation rentals; Permit Sonoma: Vacation rental permit and license application; Permit Sonoma: Vacation Rental Exclusion Combining District; County of Sonoma Clerk-Recorder: Documentary transfer tax; Justia: California Civil Code section 1102.19; Office of the State Fire Marshal: Fire hazard severity zones; California Public Law: Health and Safety Code section 13113.8; California Public Law: Health and Safety Code section 19211; California Public Law: Civil Code section 1101.4.
Monte Rio real estate FAQs
What county is Monte Rio in, and what is its ZIP code?
Monte Rio is in Sonoma County, on the lower Russian River west of Guerneville, and its ZIP code is 95462. It’s unincorporated, so county rules apply to permits, rentals and septic systems.
How much do homes cost in Monte Rio?
Redfin’s median was $475,000 for the three months ending August 2026, and Zillow’s home value index, which Zillow says uses surrounding-area data, was $520,717 at the end of September 2026. With about four sales a month, prices swing widely from one sale to the next.
Does Monte Rio flood?
Yes, on the river flat. The Weather Service expects Old Bohemian Highway to flood at 32 feet on the Guerneville gauge and the main business section at 44 feet, and the river reached 45.38 feet in February 2019. Hillside homes can stay dry while their access roads close.
Do I need flood insurance for a Monte Rio home?
Price it either way. Homeowner’s policies don’t cover flooding, a new National Flood Insurance Program policy typically takes up to 30 days to start, and a seller whose parcel is in a FEMA special flood hazard area must disclose it. Get the quote during your inspection period.
Is Monte Rio on sewer or septic?
Expect septic. The Russian River County Sanitation District serves Guerneville, Guernewood Park, Vacation Beach and Rio Nido, not Monte Rio, and septic systems within the river’s protection area, by default 600 feet of the bank, fall in Tier 3, with enhanced standards above the county’s regular septic rules.
Who provides water in Monte Rio?
The Sweetwater Springs Water District, through a Monte Rio system separate from its Guerneville one. Some outlying parcels use private wells, so confirm the source for each address.
Can I buy a Monte Rio home to use as a vacation rental?
Only with a county permit and license, and only where zoning, caps and exclusion zones allow. The county’s 2023 review recommended a 5% cap for the Monte Rio neighborhood, which was already at 12.1%, so check the parcel on the map before you buy.
Do Monte Rio vacation rentals need a property manager?
Yes. Every permitted vacation rental in the unincorporated county needs a certified vacation rental property manager, and complaints must be resolved within 30 minutes in the evening and an hour during the day. Rentals of more than 30 days don’t fall under the vacation rental rules.
Does a vacation rental permit stay with the house when I buy?
Don’t assume it does. Licenses are issued to individuals or family trusts, and in an exclusion zone an existing permit ends when the property is sold. Ask Permit Sonoma what a new owner would need.
Is Monte Rio in a high fire hazard zone?
It depends on the parcel, so look it up on CAL FIRE’s map. If it’s in a High or Very High zone, AB 38 defensible-space paperwork becomes part of the sale.
Is there a bus from Monte Rio to Santa Rosa?
Yes. Sonoma County Transit Route 20 starts at Creekside Park in Monte Rio and runs through Guerneville, Forestville and Sebastopol to the Santa Rosa Transit Mall.
What school district serves Monte Rio?
The Monte Rio Union Elementary district, whose K–8 school is on Foothill Drive. High school assignment depends on the address, so check it with the district before you buy.
Can I add an ADU to a Monte Rio property?
Often, but septic capacity usually decides it, and the ADU can’t be used as a vacation rental. Our guide to land, lots and ADUs in Sonoma County covers the county’s size limits and permits.
Sources & notes
- Redfin: Monte Rio housing market (August 2026); Zillow: Monte Rio home values (September 30, 2026); Census Reporter: Monte Rio CDP, ACS 2020–2024; C.A.R.: September 2026 sales and price report
- NOAA National Water Prediction Service: Russian River at Guerneville (GUEC1), flood categories, crests and impact statements (accessed October 2026); Sonoma County Emergency Management: February 2019 storm-flood after-action report (July 2019) and preparing for flood season
- Sweetwater Springs Water District: 2020 Urban Water Management Plan; Sonoma Water: sanitation districts
- Permit Sonoma: OWTS Manual and LAMP (2026); North Coast Regional Water Board: Russian River pathogen TMDL
- Permit Sonoma: vacation rentals, 2023 rezoning table, ordinances, exclusion districts and fire hazard severity zones; Sonoma County: transient occupancy tax
- California Department of Insurance (May 2026); Sonoma County Transit: Route 20; California State Parks: Armstrong Redwoods and Austin Creek SRA
Figures carry their dates where they appear, and we refresh market numbers every quarter. This is general information, not legal, tax or insurance advice; confirm the rules for a specific property with the agency named. Last reviewed October 2026 by Matthew Martinez.
Plan your next move
Share your preferred location, budget, property requirements and timing. We can help organize a focused search, arrange showings or discuss preparing a property for sale.
Local resource: Sonoma County community directory. Check official information for the address you are considering; area descriptions do not establish a property’s permitted uses.
