Photo: Michael Barera · CC BY-SA 4.0FEMA expects about as much hazard damage per building in Janesville as in the typical U.S. town, mostly from river and rain flooding
On FEMA’s National Risk Index, Janesville gets a B− for hazard risk: higher expected damage per building than 51% of U.S. towns, #309 of 362 in Wisconsin. Most of that expected damage is river and rain flooding (77%), then tornadoes (13%). Flood insurance has paid 52 claims here since 1979.
Graded on FEMA’s expected yearly building damage per dollar of building value (NRI v1.20, December 2025), weighted by where residents live; flood claims are shown, not graded. How hazard risk is graded
What stands out about Janesville’s natural hazards
From FEMA’s model and FEMA’s records, below.
What Janesville faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
River and rain flooding
Tornadoes
Hail
Shares are of FEMA’s expected building damage, the measure the grade uses; ranks compare each hazard’s building-damage rate with all 85,154 U.S. census tracts. In FEMA’s terms, river and rain flooding is FEMA’s “Inland Flooding” (rivers and streams overflowing their banks, or rain overwhelming drainage). FEMA defines coastal flooding as high or rising tides and storm surge, so surge damage is counted there. Drought isn’t listed: FEMA counts its losses in crops only.
What’s behind Janesville’s grade
River and rain flooding is 77% of the building damage FEMA expects in Janesville, and Janesville’s rate of river and rain flooding damage is higher than 64% of U.S. census tracts. Next is tornadoes at 13% (higher than 88% of U.S. census tracts).
B− #309 of 362 in Wisconsin; higher expected damage per building than 51% of U.S. towns (21,298).
Janesville’s residents live in 18 census tracts; FEMA’s figures are combined by where they live.
The typical Wisconsin town has lower expected damage than 79% of U.S. towns; within the state, Janesville has more expected damage per building than 85% of Wisconsin towns.
In dollars, FEMA expects about $29.1M a year in losses across Janesville: $19.5M to buildings, the rest to people and crops.
Does Janesville flood? Sometimes: 52 flood claims since 1979
Every paid claim on a federal flood insurance policy in Janesville, from FEMA’s records: 1.8 per 1,000 homes, fewer than 65% of the 13,809 U.S. towns with a flood insurance record.
- The Storm6 claims · $436K
- The 2026-04-Flooding3 claims · $56K
Janesville isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.
Insurance rates: Rock County.6 federal disasters brought FEMA money to Janesville
Disasters that paid out in Janesville itself (aid to households or repair grants to the City of Janesville), newest first, with that year’s flood claims.
- 2026Severe Storms, Tornadoes, and Flooding723 households applied for aid$3.2M aid approved$77K to the City of Janesville for repairs3 flood claims paid that year
- 2008Severe Storms, Tornadoes, and Flooding324 households applied for aid$691K aid approved$658K to the City of Janesville for repairs
- 2008Record Snow and Near Record Snow$68K to the City of Janesville for repairs
- 2007Severe Storms and Flooding54 households applied for aid$27K aid approved
- 2004Severe Storms and Flooding2 households applied for aid$2K aid approved3 flood claims paid that year
- 2000Snow$39K to the City of Janesville for repairs
Rock County has had 13 natural disasters declared by the President since 1953, most often severe storms, then floods. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Old photos of Janesville after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Janesville archive →Janesville and its neighbors
Janesville is 3rd of the 4 graded towns here, from least expected damage per building to most. Tap a town to see its hazards.
| Town | Hazard risk | Mostly (buildings) | Flood claims |
|---|---|---|---|
| Janesville | A−less damage than 81% | river and rain flooding | 26 |
| Rock | B+less damage than 66% | river and rain flooding | 25 |
| Janesville | B−more damage than 51% | river and rain flooding | 52 |
| Harmony | C+more damage than 60% | river and rain flooding | 1 |
| La Prairie | — | 839 residents; we grade 1,000+ | |
Hazard risk = FEMA’s expected yearly building damage per dollar of building value, vs. the 21,298 U.S. towns we grade; the map is shaded by fifths of the same scale. Flood claims = paid federal flood insurance claims on record.
Get ready for what Janesville faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Turn around at flooded roads: a foot of moving water can carry off a car.
- Flood insurance usually takes 30 days to start, so buy it before the forecast.
- Keep papers and medicines up high, in a grab-and-go bag.
- Pick your spot now: the lowest floor, an inside room, no windows.
- A watch means be ready; a warning means take cover now.
- Keep shoes and a flashlight by the bed.
- Park in a garage or under cover when storms are forecast.
- Stay away from windows while it falls.
- Photograph roof and car damage for your insurer.
- Look up the address on FEMA’s flood map.
- Ask the seller or landlord whether it has ever flooded, and what flood insurance costs there.
- Get a flood insurance quote early: policies usually start 30 days after you buy.
Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.
Questions about natural hazards in Janesville
Is Janesville at risk for natural disasters?
On FEMA’s National Risk Index, Janesville has higher expected damage per building than 51% of U.S. towns: B− for hazard risk, #309 of 362 in Wisconsin. Most of the expected damage is river and rain flooding (77%) and tornadoes (13%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Janesville flood?
Flood insurance has paid 52 claims in Janesville since 1979, $986K in all, or 1.8 per 1,000 homes, fewer than 65% of U.S. towns with a flood insurance record. 3 properties have flooded more than once. The most claims came from Storm (6).
Is Janesville in a flood zone?
Flood zones are drawn street by street, so the answer depends on the address: look it up on FEMA’s flood map. In Rock County, 33% of homes in mapped flood zones carry federal flood insurance, and 0.4% of all homes do.
How much is flood insurance in Janesville?
FEMA’s Community Rating System list shows no discount for Janesville’s flood program. Premiums depend on the building; policies usually start 30 days after you buy, so get a quote early.
What was the biggest storm in Janesville?
By FEMA money that reached Janesville, Severe Storms, Tornadoes, and Flooding (2026): 723 households applied for aid, $3.2M approved, and $77K to the City of Janesville for repairs. By flood claims, Storm: 6 paid, $436K.
Is Janesville at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (77%), and Janesville’s rate for it is higher than 64% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Janesville.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Janesville’s residents lived in the 2020 census; OpenFEMA: NFIP redacted claims, multiple-loss properties, community status book and residential penetration rates, housing assistance (owners and renters), public assistance funded projects, hazard mitigation properties and disaster declarations. Homes: Census ACS 2020–24. Preparedness tips: Ready.gov. FEMA’s model is an average of expected damage, not a forecast. How hazard risk is graded.