Enter any address in Lewis and Clark County, Montana to see its FEMA flood zone
Flash flooding from thunderstorms is a significant flood character in Lewis and Clark County. Over the last 30 years, NOAA Storm Events data shows 21 flash flood events and 18 flood events. For example, an upper-level trough contributed to thunderstorms and flash flooding across Southwest Montana in September 2024, with one event impacting the Horse Gulch burn scar. In June 2023, heavy rain and thunderstorms caused flash flooding across portions of the Rocky Mountains.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone A have experienced an average of $3,651 in payouts with an average water depth of -1.2 feet. Zone X_SHADED properties have seen higher average payouts of $5,627 with an average water depth of 1.3 feet. Homeowners in Zone A, Zone X_SHADED, and properties located near area creeks and streams should pay particular attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
15 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Lewis and Clark County, Montana has recorded 39 flood-related events since 1996 according to NOAA's Storm Events Database, including 21 flash floods and 18 river or area floods. The county has received 16 federal disaster declarations, 3 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1975–2024)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Horse Gulch Fire | Fire | Jul 9, 2024 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| North Hills Fire | Fire | Jul 26, 2019 |
| Flooding | Flood | May 1, 2018 |
| Alice Creek Fire | Fire | Sep 8, 2017 |
| Corral Fire | Fire | Jun 25, 2012 |
| Severe Storms And Flooding | Severe Storm | Apr 4, 2011 |
| Country Club Fire | Fire | Sep 16, 2007 |
| Hurricane Katrina Evacuation | Hurricane | Aug 29, 2005 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Sep 11, 2024 | 0.00K |
| Flash Flood | Jun 10, 2023 | 0.00K |
| Flood | Apr 9, 2023 | 100.00K |
| Flood | Jun 8, 2023 | 0.00K |
| Flash Flood | Jul 3, 2022 | 0.00K |
| Flash Flood | Jul 3, 2022 | 700.00K |
| Flood | Jun 30, 2020 | 0.00K |
| Flood | May 26, 2019 | 0.00K |
| Flood | Apr 29, 2018 | 0.00K |
| Flood | Apr 27, 2018 | 0.00K |
Flash Flood — Sep 11, 2024
An upper level trough passed across the Northern Rockies September 11, which allowed for numerous thunderstorms to develop in the afternoon. Thermodynamic and kinematic ingredients were sufficient for a few strong thunderstorms, mostly across Southwest Montana. Additionally, a series of thunderstorms moved across the Horse Gulch burn scar, which resulted in flash flooding.
Flash Flood — Jun 10, 2023
Several rounds of rain and thunderstorms affected much of Montana during the first half of June. Flash flooding occurred across portions of the region, especially across Fergus County as well as the Rocky Mountains. Fergus County was hit exceptionally hard as several days of occasional heavy rain exasperated area creeks and streams. Casino Creek, located south of Lewistown, was washed out in at...
Flood — Apr 9, 2023
Unseasonably warm temperatures occurred in the first two weeks of April, with highs near 80 degrees occurring at times. These warm temps, along with occasional rain, resulted in melting of a deep snowpack on top of frozen ground which led to significant runoff into area waterways. Moderate to major flooding occurred along portions of the Milk River and its tributaries. Impactful snowmelt floodi...
Flood — Jun 8, 2023
Several rounds of rain and thunderstorms affected much of Montana during the first half of June. Flash flooding occurred across portions of the region, especially across Fergus County as well as the Rocky Mountains. Fergus County was hit exceptionally hard as several days of occasional heavy rain exasperated area creeks and streams. Casino Creek, located south of Lewistown, was washed out in at...
Flash Flood — Jul 3, 2022
Low pressure along the west coast spread deeper moisture increasing the chances for showers and thunderstorms across the region through Independence Day. These storms brought strong, gusty winds, severe hail, moderate to heavy rainfall, and lightning, causing notable damage to property, specifically crops.
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in Lewis and Clark County, Montana:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in Lewis and Clark County, Montana that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.