Weather & Climate in Roundup, MT

Temperature, precipitation, air quality, natural hazards, and monthly weather data.

Roundup experiences four distinct seasons with an average annual temperature of 47°F (8°C). Winters average 25°F in January while summers reach 71°F in July. The area gets 273 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 14.9 inches (drier than the 38-inch national average). The area receives 24.4 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 26 / among the cleanest air in the country. The city sits at an elevation of 3,226 feet.

Temperature

25°F Jan (-4°C) 71°F Jul (22°C)

Annual Average	46.5°F
	14% below US avg
January Average	25°F (-4°C)
July Average	71°F (22°C)
Sunny Days	273 days/yr

Geography

Elevation	3,226 ft (983 m)
Area	1.3 sq mi (3.3 km²)
Population Density	1,522/sq mi
Coordinates	46.4483°N, 108.5397°W
Timezone	America/Denver
County	Musselshell County County
Nearest Airport	Billings Logan International (BIL) 44 miles away

Precipitation & Snow

Annual Rainfall 14.9"

61% below US avg

Snowfall 24.4"

Wettest Month (May) 2.56"

Driest Month (Feb) 0.35"

Air Quality

AQI Median	26.0
Rating	Good

Natural Hazard Risk

Overall Risk	Very Low
Risk Score	17.1 / 100
Social Vulnerability	74.3 / 100
Community Resilience	25.1 / 100

Hazard Breakdown

Tornado	Very Low
Earthquake	Very Low
Wildfire	Relatively Moderate
Flood	Very Low
Hail	Relatively Low
Strong Wind	Very Low
Heat Wave	Very Low
Winter Weather	Relatively Moderate
Lightning	Relatively Moderate
Ice Storm	Very Low
Drought	Very Low
Cold Wave	Relatively Moderate
Landslide	Relatively Low

Source: FEMA National Risk Index v1.20 (Dec 2025)

Earthquake History

7 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.7.

Jan 9, 2003	23 km E of Wilsall, Montana	M3.7	148 km	11 km
Jul 6, 2021	27 km SSE of Melstone, Montana	M3.6	61 km	10 km
Jul 21, 2023	Eastern Montana	M3.2	108 km	5 km
May 21, 2013	32 km NE of Melstone, Montana	M2.8	86 km	7 km
Nov 4, 2017	32 km NE of Wilsall, Montana	M2.7	140 km	4 km
Oct 16, 2011	Eastern Montana	M2.7	108 km	21 km
Jan 8, 2003	24 km E of Wilsall, Montana	M2.5	147 km	14 km

Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.

Tornado History

47 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 6 injuries.

Date	Rating	Distance	Path	Fatalities
Jun 16, 1965	EF3	72 km	20.6 mi	0
Jun 20, 2010	EF2	71 km	0.7 mi	0
Aug 14, 1999	EF2	96 km	5.0 mi	0
May 4, 1986	EF2	37 km	0.1 mi	0
Jul 20, 1964	EF2	97 km	2.0 mi	0
Aug 7, 1962	EF2	95 km	2.0 mi	0
Jul 2, 1958	EF2	72 km	0.5 mi	0
May 21, 2016	EF1	45 km	2.0 mi	0
Jun 21, 1991	EF1	72 km	0.2 mi	0
May 24, 1990	EF1	56 km	0.2 mi	0
Aug 12, 1958	EF1	86 km	0.5 mi	0
Jul 6, 1955	EF1	66 km	2.0 mi	0
Jul 7, 2020	EF0	60 km	0.1 mi	0
Jul 7, 2020	EF0	81 km	0.2 mi	0
Jul 8, 2013	EF0	54 km	0.5 mi	0
Jun 6, 2011	EF0	71 km	0.0 mi	0
Jun 6, 2011	EF0	57 km	0.3 mi	0
Aug 11, 2005	EF0	75 km	9.0 mi	0
Jun 28, 2005	EF0	93 km	0.3 mi	0
Jun 28, 2005	EF0	62 km	2.0 mi	0

Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: HAWK CREEK (157,778 acres, 1984).

Year	Name	Acres Burned	Distance
1984	HAWK CREEK	157,778	30 km
2008	DUNN MTN. ASSIST	105,494	37 km
2006	PINE RIDGE COMPLEX	103,074	82 km
2006	BUNDY RAILROAD	91,575	58 km
2012	DELPHIA	40,396	31 km
2020	BOBCAT	31,020	20 km
1999	FISHEL CREEK	28,611	36 km
2021	MUSSELSHELL TRAIL RD	22,723	66 km
2012	DAHL	21,448	19 km
2022	BUSMAN ROAD	12,584	87 km
1994	GRIERSON	7,985	68 km
1998	BURNT SHED	6,395	48 km
2015	3 HL TIN CAN UNIT F PRESCRIBED FIRE	5,911	94 km
2006	MAILBOX	5,741	67 km
1996	LASTSTAND	5,385	98 km
2021	PETERSON	5,006	51 km
1999	HORSE THIE	4,767	21 km
2015	TROPHY RIDGE	4,478	96 km
2000	PEASE	4,361	81 km
2006	EMERALD HILLS	4,191	75 km

Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	25°F (-4°C)	0.5 in	Coldest
February	28°F (-2°C)	0.4 in	Driest
March	35°F (2°C)	0.6 in
April	44°F (7°C)	1.1 in
May	54°F (12°C)	2.6 in	Wettest
June	63°F (17°C)	2.2 in
July	71°F (22°C)	1.3 in	Warmest
August	69°F (21°C)	1.3 in
September	58°F (15°C)	1.3 in
October	47°F (9°C)	0.9 in
November	35°F (1°C)	0.4 in
December	26°F (-3°C)	0.5 in

Roundup has a seasonal temperature swing of 46°F / from 25°F in January to 71°F in July. Total annual precipitation is 13.1 inches, with May being the wettest month (2.6") and February the driest (0.4").

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