Wildfire risk in Colusa County: where it is highest, and why
Wildfire risk in Colusa County spans a wide range across the places we scored. The lowest score is 18.6 in Williams, the highest is 83.5 near Williams, and the middle score is 37.2.
Colusa County — the largest fires on record, at their perimeter centres, with the county’s main communities. Select a marker for its detail.
At a glance
Half of Colusa County scores Moderate or worse
We scored 154 points across Colusa County on the same 0–100 scale a Satelife address report uses, and they do not land in one place. 10% of them come out Very High, while 26% are Low. Which end your own parcel sits at is not something a county map can tell you.
10%
36%
28%
26%
Very High10% · 16 of 154 pointsHigh36% · 55 of 154 pointsModerate28% · 43 of 154 pointsLow26% · 40 of 154 points
Safest end we measured18.6near Williams · Low
Middle of the county37.2Moderate — half of Colusa County is above this
Most exposed end we measured83.5near Williams · Very High
And the federal models agree it is a fire county
Relatively ModerateFEMA National Risk Index — wildfire risk rating · index score 89.1 / 100
$1.1M / yrFEMA NRI — expected annual loss from wildfire · rated Relatively Moderate
1.70%USFS Wildfire Risk to Communities — mean annual burn probability · 90th-percentile cell 4.18%
5.38 ftUSFS WRC — mean conditional flame length · 85% of the county carries burnable fuel
FEMA NRI also rates Colusa County: all-hazards risk Relatively Moderate · social vulnerability Relatively Moderate · community resilience Relatively Low · annualised wildfire frequency 0.0051.
Sources: FEMA National Risk Index 1.20.0 (Dec 2025), county record · USFS Wildfire Risk to Communities v2.0, mean of the grid cells inside the county. Both describe the county as a whole, never an address in it.
What does your Colusa County address score?
A county range shows the spread. Your parcel sits somewhere inside it — the report says where, and what to do about it.
Free to request · PDF report with a 0–100 score, the drivers behind it, and a mitigation plan
Local context
What the data says about Colusa County
Looking at the four address-style tiers, High has the most scored points, with 55. Very High has 16 points, so those areas are present but not the majority.
For countywide context, FEMA’s National Risk Index rates Colusa County’s wildfire risk as Relatively Moderate. FEMA also rates the county’s expected annual wildfire loss as Relatively Moderate.
Fire record
Where the fires actually were
Since 1984, 195,498 acres have burned within county fire perimeters, and that equals 26.6% of the county. There have been 38 fire perimeters in that period.
The largest named large fire in the county summary is the Fork fire (1996), at 83,057 acres.
The most recent large fire is the Sites fire (2024), at 19,195 acres.
Ranch Fire, 2018 — Colusa County.
Photo: MODIS Land Rapid Response Team, NASA GSFC · Public domainSites Fire, 2024 — Colusa County.
Photo: MODIS Land Rapid Response Team, NASA GSFC · Public domain
38mapped fire perimeters centred in the county since 1984
195,498acres inside those perimeters since 1984
26.6%of the county's area, as a share of 2,979.2 km²
Sites 2024most recent large fire on record
Before 20002000s2010s2020s
Fire perimeters coloured by decade. Select a perimeter for its name, year and size.
Named fires on record
Ranch Fire2018410,202 acres in totalcrossed into the county
Fork Fire199683,057 acres
Mill Fire201229,525 acres
Sites Fire202419,195 acres
Sixteen Fire201217,942 acres
Little Stoney Fire195017,367 acres
Cortina Ridge Fire196616,323 acres
Walker Wye Fire20127,934 acres
Perimeter sources: NIFC Interagency Fire Perimeter History · WFIGS Interagency Perimeters · largest on record: Fork 1996.
Perimeters are simplified for display; acreage is the figure the source records.
Communities
Where in the county you are matters most
Among the named communities shown here, Maxwell has the highest middle wildfire risk score at 30.5. Colusa is close at 29.6, while Williams is lower at 23.6.
Princeton’s middle score is 25.1, between Williams and Colusa. In population terms, Colusa (6,060) and Williams (4,723) are the two largest communities listed here.
Maxwellvillage · 1,103 people
30.5 Moderate
Colusatown · 6,060 people
29.6 Moderate
Princetonvillage
25.1 Moderate
Williamsvillage · 4,723 people
23.6 Low
The score is the median of the sampled points nearest that community — a community-scale
indicator, not a score for any individual property in it. Population comes from the
community's own record where the source carries one.
Terrain & fuels
Terrain, vegetation and fuels
Terrain scores are low in many scored places: the middle value is 20.0, and a low point of 20.0 appears near Williams. The terrain high point is 65.0 near Maxwell.
Vegetation and fuels are more elevated than terrain in many locations. The middle vegetation-and-fuels score is 55.0, with a high of 80.0 near Williams and a low of 20.0 in Williams.
20median terrain score (max 65 near Maxwell)
55median vegetation & fuels score (max 80 near Williams)
Fire weather
Fire weather across Colusa County
Fire weather was measured across the county, and scores are consistently high. Values run from 64.6 in unincorporated Colusa County to 73.4 in Princeton, with a middle value of 65.2.
A separate national model from the USFS Wildfire Risk to Communities reports a mean annual burn probability of 1.70% and a 90th-percentile cell burn probability of 4.18%. It also shows 85.4% of the county as land that can burn; this is a burn-probability model, not a fire-weather rating.
64.6lowest fire-weather score — near unincorporated Colusa County
73.4highest fire-weather score — near Princeton
What drives it
Which part of the risk moves, and which doesn't
Risk is not even from place to place in the county. The overall score reaches 83.5 near Williams, while Williams also contains the county low point at 18.6.
Hazard zone scores also vary sharply, from 10.0 near Williams up to 95.8 near Williams, with a middle value of 35.4.
Fire history scores run from 5.0 near Williams to 95.0 near Maxwell, with a middle value of 30.0.
Each bar is what one part of the score covers across Colusa County, on the same 0–100 scale.
A long bar is a part of the risk that depends on where you are; a short one is the same
almost everywhere.
Terrain
20–65highest near Maxwell
Vegetation & fuels
20–80highest near Williams
Hazard zone
10–95.8highest near Williams
Fire history
5–95highest near Maxwell
Fire weather
64.6–73.4highest near Princeton
Overall score
18.6–83.5highest near Williams
The tick on each bar is the middle value. Tier boundaries — Moderate at 25, High at 50,
Very High at 75 — are the faint lines behind them.
Show every number behind these bars
Layer
Min
Median
Max
Lowest place
Highest place
Points
Terrain
20
20
65
near Williams
near Maxwell
154
Vegetation & fuels
20
55
80
Williams
near Williams
154
Hazard zone
10
35.4
95.8
near Williams
near Williams
154
Fire history
5
30
95
near Williams
near Maxwell
154
Fire weather
64.6
65.2
73.4
unincorporated Colusa County
Princeton
154
Composite
18.6
37.2
83.5
Williams
near Williams
154
Independently of Satelife's layers, the USFS Wildfire Risk to Communities grid puts the county's mean annual burn probability at 1.70% (90th percentile cell: 4.18%), with a mean conditional flame length of 5.38 ft. 85% of the 25,727 grid cells inside the county carry burnable fuel at all.
Source: USFS Wildfire Risk to Communities v2.0 (ImageServer, county extent).
CAL FIRE has no mapped Fire Hazard Severity Zone at 29 of the 154 sampled points — the zones cover Local Responsibility Areas. At 28 of them the USFS grid above supplied the hazard reading instead; at the remaining 1 the hazard weight is renormalised away rather than scored as low.
154 sample points on a ~2.3 km grid, plus one at the centre of each community, weighted with the Satelife county profile v1 · median layer coverage 100%. Scores are 0–100 and comparable within the county, not across states.
For a property
What a county range means for one address
Property-specific features like roof type, vents, and defensible space were not measured at all in this county view.
What this county view does show is how risk around properties can differ by location. High is the most common tier in the scored points (55), and Very High is also present (16).
Local context matters: one of the highest nearby scores is 83.5 near Williams, while a low point of 18.6 is in Williams. That spread is why parcel-level reports focus on the exact address and its immediate surroundings.
Across 154 sampled points in Colusa County, the score runs from
18.6 to 83.5 — two neighbouring parcels can sit in different tiers.
A county number is the middle of that spread; it says nothing about which end yours is at.
Find out where your Colusa County parcel sits
Slope, the fuel touching the structure, the road out, the fire history within a mile — measured at your address, not averaged across the county.
Free to request · PDF report with a 0–100 score, the drivers behind it, and a mitigation plan
Coverage
ZIP codes we cover in Colusa County
Every one of the 18 ZIP areas that touch Colusa County — we run address-level
reports in all of them. They are grouped by the median score of the points we sampled inside
each, which is a neighbourhood-scale indicator and not a score for any
property: two homes in the same ZIP routinely land in different tiers.
Frequently asked questions about Colusa County wildfire risk
What is the latest large fire in Colusa County?
The most recent large fire is Sites (2024), at 19,195 acres. The largest named large fire in the county summary is Fork (1996), at 83,057 acres.
How much of the county has burned since 1984?
26.6% of Colusa County has burned since 1984, totaling 195,498 acres within recorded fire perimeters.
Does most of the county fall in the highest risk tier?
No. High is the most common tier in the scored points (55), while Very High has 16 points.
How does FEMA rate wildfire risk for the county?
FEMA’s National Risk Index rates Colusa County’s wildfire risk as Relatively Moderate, and its expected annual wildfire loss from wildfire as Relatively Moderate.
Is the USFS burn probability the same thing as fire weather?
No. Fire weather scores in the county run from 64.6 to 73.4, while the USFS model reports burn probability (1.70% mean annual, 4.18% at the 90th-percentile cell). They are different measures.
This page is generated from a Colusa County data pack assembled on 2026-08-19 (pack v1.0). Scores are sampled across the
county, not measured at any individual address, and are informational decision support — not a
substitute for official evacuation orders, a fire-agency hazard determination, or an insurer's
underwriting judgement.
Data versions: fema_nri 1.20.0 (Dec 2025) · landfire per adapter · nifc_history All Years View · wfigs current · wrc v2.0 (2024) · zcta Census 2020.
What does your parcel look like, layer by layer?
A county range shows the spread. An address-level Satelife report shows where in that spread your property actually sits — PDF, per-layer score, and a prioritized mitigation plan.
