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Risk: Very Low

Custer County, MT Environment & Hazard Risk

Very Low natural hazard risk, led by cold wave. 557 storm events since 1996.

Expected yearly loss
$10.3M
Very Low nationally
Storm events since 1996
557
Most often hail
Flood insurance policies
687
11.7% of homes
Hurricanes nearby
0
Since 1851

Natural hazard risk

FEMA National Risk Index, December 2025

Overall risk

Very Low

Score 42.1 of 100

Social vulnerability

Relatively High

Score 70.8 of 100

Community resilience

Relatively Low

Score 27.1 of 100

Community resilience runs the other way: a higher rating means a community can recover faster.

Building value exposed: $3.5B · Agriculture value exposed: $98.6M · Risk-adjusted yearly loss: $13.8M

Risk by hazard

  • Cold waveRelatively Moderate$4.3M/yr expected annual loss, about 6.3 events a year
  • Winter weatherRelatively High$230K/yr expected annual loss, about 16 events a year
  • WildfireRelatively Low$550K/yr expected annual loss, about once every 189 years
  • LightningRelatively Moderate$493K/yr expected annual loss, about 31 events a year
  • Strong windRelatively Moderate$575K/yr expected annual loss, about once every 1 year
  • LandslideVery Low$1,966/yr expected annual loss, about 2.9 events a year
  • HailRelatively Low$184K/yr expected annual loss, about 1.8 events a year
  • Heat waveVery Low$162K/yr expected annual loss, about 2.2 events a year
  • EarthquakeVery Low$67.6K/yr expected annual loss, about once every 4,651 years
  • DroughtVery Low$12.8K/yr expected annual loss, about 61 events a year
  • TornadoVery Low$126K/yr expected annual loss, about once every 4 years
  • Ice stormVery Low$3,963/yr expected annual loss, about once every 67 years

Bars show the national percentile score (0 to 100) for each hazard. Dollar figures are expected annual losses to buildings, people and crops. Not rated here: avalanche, coastal flooding, hurricane, riverine flooding, tsunami, volcanic activity.

Flood risk and insurance

National Flood Insurance Program and FEMA flood maps

Check the flood zone for an address

Homes with flood insurance
687 of 5,878 (11.7%)
Homes in high-risk flood zones
3,018
Insured in high-risk zones
670 (22%)
Flood claims since 1978
156
Claims paid since 1978
$400K

Flood claims paid per year

Flood claims paid per year in Custer County
Beta

Storm history

Since 1996: 557 events, 2 deaths, $2.4M in damage

  • Hail200
  • Thunderstorm Wind170 · 1 death
  • High Wind53
  • Winter Storm32
  • Heavy Snow32
  • Flash Flood20
  • Blizzard12
  • Flood11
  • Heavy Rain7
  • Funnel Cloud5
Beta

Events per year

Storm events per year in Custer County
15
17
15
16
23
12
31
11
23
19
9
28
15
25
11
15
16
23
18
8
Beta

8 tornadoes on record (EF0 1, EF1 1, F0 4, F2 2).

Most damaging storms

Since 1996, ranked by deaths, injuries and damage

  • Thunderstorm Wind70 kt wind07/06/2016

    Kinsey, Custer County

    1 death, 1 injured

    What happened

    A semi truck was blown off Interstate 94 at Mile Marker 156. The driver of the semi was injured.

  • Lightning06/26/1999

    Mizpah, Custer County

    1 death

    What happened

    A 14 year-old boy was struck and killed by lightning while standing on a front tire of a tractor in a field.

  • Thunderstorm Wind65 kt wind07/14/2024

    Miles City, Custer County

    3 injured

    What happened

    Several injuries occurred due to trees falling on them and vehicles. At least one person was hospitalized.

  • Thunderstorm Wind07/10/2000

    Miles City, Custer County

    2 injured, $15K damage

    What happened

    2 inch diameter hail. Crop and window damage. Foot of water over Frontage Road along Interstate 94. Interstate 94 closed for one hour due to water over the road. Car accident near mile marker 160 with two injuries.

  • Flood05/21/2011

    Knowlton, Custer County

    $1.1M damage

    What happened

    Significant flooding occurred on creeks and streams across Custer County with numerous county roads flooded, closing roads and resulting in significant damage. At the height of the flooding, emergency only travel was advised due to the magnitude of the event. The Powder River near Locate rose above flood stage from May 10th through May 23rd. The river crested four times at 11.29 feet, 11.70 feet, 11.27 feet and 9.28 feet on the 10th, 21st, 22nd and 23rd respectively. In addition, Pumpkin Creek was reported to be flowing over Highway 59 southeast of Miles City. Pumpkin Creek had a record crest of 13.98 feet on May 20th and 21st. The Yellowstone River at Miles City went above flood stage from May 22nd through May 29th. The river crested at 14.74 feet on the 24th and 14.53 feet on the 29th. The Tongue River at Miles City rose above flood stage from May 11th through May 23rd and crested at a record 13.99 feet on May 21st. Damage estimates based on FEMA reviews and Individual Assistance approvals.

  • Flash Flood07/05/1998

    Miles City, Custer County

    $1M damage

    What happened

    Several streets were closed in Miles City because of flash flooding. Basements of several homes and businesses were flooded.

Drinking water

4 community water systems serve about 10,288 people. Violations since 2021.

2 systems had health-based violations, such as a contaminant over the legal limit or a missed treatment step.

Largest systems by population served. Monitoring and reporting violations mean required tests or notices were late or missing, not that the water was unsafe.

Pollution sites

0 Superfund sites and 1 toxic release facility in Custer County

Superfund sites

None in this county.

Toxic release facilities

Superfund sitesToxic release facilitiesEPA inspections and enforcementAir toxics cancer risk12 historic places

Frequently asked questions

How risky is Custer County for natural disasters?
FEMA rates Custer County very low for overall natural hazard risk, with expected losses of $10.3M a year. The highest-rated hazards are cold wave (relatively moderate), winter weather (relatively high), wildfire (relatively low).
What storms are most common in Custer County?
Since 1996, NOAA recorded 557 storm events affecting Custer County, most often hail (200), thunderstorm wind (170), high wind (53).
How many tornadoes have hit Custer County?
8 tornadoes have been recorded in Custer County since 1950.
How many homes in Custer County have flood insurance?
687 residential flood insurance policies are in force in Custer County, covering about 11.7% of homes. The program has paid $400K on 156 claims here since 1978.
What is the weather like in Custer County?
At Mizpah 4 Nnw, average highs reach 91°F in Jul and lows fall to 6°F in Jan, with 14.5 inches of rain a year (1991-2020 normals).

Source: FEMA (National Risk Index, NFIP), NOAA (Storm Events, HURDAT2, Climate Normals), EPA · Last updated 08/01/2026 · Storm counts include events in forecast zones that touch the county. This product uses the FEMA OpenFEMA API, but is not endorsed by FEMA.

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