Weather & Climate in Roy, MT

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

Roy has a cool climate with an average annual temperature of 45°F (7°C). Winters average 22°F in January while summers reach 70°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 13.3 inches (drier than the 38-inch national average). The area receives 36.3 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 3,490 feet.

Temperature

22°F Jan (-5°C) 70°F Jul (21°C)

Annual Average	45.4°F
	16% below US avg
January Average	22°F (-5°C)
July Average	70°F (21°C)
Sunny Days	273 days/yr

Geography

Elevation	3,490 ft (1,064 m)
Area	3.4 sq mi (8.8 km²)
Population Density	39/sq mi
Coordinates	47.3343°N, 108.9600°W
Timezone	America/Denver
County	Petroleum County County
Nearest Airport	Billings Logan International (BIL) 107 miles away

Precipitation & Snow

Annual Rainfall 13.3"

65% below US avg

Snowfall 36.3"

Wettest Month (May) 2.87"

Driest Month (Feb) 0.39"

Air Quality

AQI Median	26.0
Rating	Good

Natural Hazard Risk

Overall Risk	Very Low
Risk Score	1.3 / 100
Social Vulnerability	27.4 / 100
Community Resilience	12.9 / 100

Hazard Breakdown

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

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

Earthquake History

6 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.6.

Jul 6, 2021	27 km SSE of Melstone, Montana	M3.6	141 km	10 km
Dec 5, 1991	15 km WSW of Hays, Montana	M3.0	69 km	10 km
May 21, 2013	32 km NE of Melstone, Montana	M2.8	126 km	7 km
Oct 16, 2011	Eastern Montana	M2.7	44 km	21 km
Jul 10, 2021	24 km SSE of Malta, Montana	M2.7	126 km	10 km
Jul 15, 2015	48 km E of Zortman, Montana	M2.5	101 km	23 km

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

Tornado History

52 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 5 injuries.

Date	Rating	Distance	Path	Fatalities
Jul 5, 1988	EF3	78 km	3.0 mi	0
Jul 5, 1988	EF3	93 km	10.0 mi	0
Jul 8, 2002	EF2	31 km	10.0 mi	0
Aug 14, 1999	EF2	46 km	5.0 mi	0
Jun 25, 1996	EF2	64 km	2.0 mi	0
May 28, 1981	EF2	7 km	1.5 mi	0
Jun 8, 1976	EF2	84 km	0.1 mi	0
Aug 7, 1962	EF2	42 km	2.0 mi	0
Apr 22, 2003	EF1	98 km	2.0 mi	0
Aug 23, 1998	EF1	64 km	3.5 mi	0
May 10, 1977	EF1	85 km	0.1 mi	0
May 10, 1977	EF1	93 km	0.1 mi	0
Jul 7, 1957	EF1	88 km	1.5 mi	0
Jul 7, 2020	EF0	59 km	0.1 mi	0
Jul 7, 2020	EF0	37 km	0.2 mi	0
Jun 27, 2019	EF0	81 km	0.3 mi	0
Jun 27, 2019	EF0	71 km	0.1 mi	0
May 9, 2018	EF0	78 km	0.7 mi	0
Jun 5, 2012	EF0	75 km	3.8 mi	0
Jun 28, 2005	EF0	54 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: BRIDGE COULEE (222,571 acres, 2017).

Year	Name	Acres Burned	Distance
2017	BRIDGE COULEE	222,571	91 km
2017	SOUTH BREAKS	39,217	99 km
2006	LOST CREEK (BLACK PULASKI COMPLEX)	38,550	95 km
2006	SODA CREEK (BLACK PULASKI COMPLEX)	33,767	75 km
2010	RAVEN	26,631	61 km
1990	VETERANS	23,660	94 km
2021	TAYLOR	21,704	54 km
2021	PINE GROVE	16,158	77 km
2006	LODGEPOLE (BLACK PULASKI COMPLEX)	15,248	81 km
2021	SOUTH MOCCASIN	12,727	46 km
2009	MEISSNER	12,318	99 km
2012	WOLF CREEK	12,168	60 km
2017	JULY	11,409	68 km
1994	CK CREEK	11,206	70 km
2012	ESTER LAKE	10,898	95 km
2019	RIDGETOP	10,316	55 km
1996	ALKALIE	10,044	74 km
2012	WELLS	9,921	84 km
2017	CRYING	7,497	73 km
2018	3 2 1 HL LOWER CROOKED CREEK UNIT D RX FY 18	6,791	62 km

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

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	22°F (-5°C)	0.6 in	Coldest
February	27°F (-3°C)	0.4 in	Driest
March	34°F (1°C)	0.7 in
April	44°F (7°C)	1.1 in
May	54°F (12°C)	2.9 in	Wettest
June	63°F (17°C)	2.4 in
July	70°F (21°C)	1.7 in	Warmest
August	68°F (20°C)	1.6 in
September	57°F (14°C)	1.3 in
October	46°F (8°C)	0.8 in
November	32°F (0°C)	0.5 in
December	23°F (-5°C)	0.6 in

Roy has a seasonal temperature swing of 48°F / from 22°F in January to 70°F in July. Total annual precipitation is 14.5 inches, with May being the wettest month (2.9") and February the driest (0.4").

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