Weather & Climate in Thornton, CO

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

Thornton experiences four distinct seasons with an average annual temperature of 49°F (9°C). Winters average 21°F in January while summers reach 72°F in July. The area gets 321 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 24.3 inches (drier than the 38-inch national average). The area receives 30.7 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 5,197 feet.

Temperature

21°F Jan (-6°C) 72°F Jul (22°C)

Annual Average	48.7°F
	10% below US avg
January Average	21°F (-6°C)
July Average	72°F (22°C)
Sunny Days	321 days/yr

Geography

Elevation	5,197 ft (1,584 m)
Area	36.0 sq mi (93.1 km²)
Population Density	3,912/sq mi
Coordinates	39.9204°N, 104.9414°W
Timezone	America/Denver
County	Denver County County
Nearest Airport	Denver International (DEN) 15 miles away

Precipitation & Snow

Annual Rainfall 24.3"

36% below US avg

Snowfall 30.7"

Wettest Month (May) 2.52"

Driest Month (Jan) 0.51"

Air Quality

AQI Median	41.0
Rating	Good

Natural Hazard Risk

Overall Risk	Relatively High
Risk Score	95.2 / 100
Social Vulnerability	17.8 / 100
Community Resilience	68.5 / 100

Hazard Breakdown

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

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

Earthquake History

16 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.0.

Dec 25, 1994	9 km NE of Larkspur, Colorado	M4.0	71 km	10 km
Dec 23, 1995	7 km WNW of Rock Creek Park, Colorado	M3.5	132 km	5 km
Jan 18, 1997	8 km SE of Westcreek, Colorado	M3.3	92 km	5 km
Jun 1, 2014	9 km NNW of Kersey, Colorado	M3.2	67 km	1 km
Jul 22, 2001	6 km WNW of Woodland Park, Colorado	M3.1	101 km	5 km
Sep 12, 1990	13 km NW of Silverthorne, Colorado	M3.0	111 km	5 km
Feb 26, 2008	29 km WNW of Westcreek, Colorado	M2.9	85 km	2 km
Jan 19, 1997	8 km SE of Westcreek, Colorado	M2.9	92 km	5 km
Mar 30, 2019	7 km NE of Greeley, Colorado	M2.9	66 km	6 km
Dec 31, 1995	6 km WNW of Rock Creek Park, Colorado	M2.8	134 km	5 km
Jun 21, 2018	16 km SSW of Walden, Colorado	M2.7	143 km	2 km
Jan 19, 1997	8 km SE of Westcreek, Colorado	M2.7	92 km	5 km
Apr 18, 1998	8 km SE of Westcreek, Colorado	M2.7	92 km	5 km
Jun 13, 2025	7 km SE of Erie, Colorado	M2.7	10 km	9 km
Aug 23, 2016	2 km SSE of Eaton, Colorado	M2.6	68 km	10 km
Jun 23, 2014	6 km NNE of Kersey, Colorado	M2.5	67 km	5 km

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

Tornado History

750 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 1 fatality, 159 injuries.

Date	Rating	Distance	Path	Fatalities
Jun 4, 2015	EF3	39 km	6.7 mi	0
May 22, 2008	EF3	38 km	38.7 mi	1
Jun 15, 1988	EF3	21 km	2.5 mi	0
Jun 12, 1982	EF3	37 km	3.0 mi	0
May 18, 1975	EF3	23 km	4.1 mi	0
May 15, 1952	EF3	55 km	7.4 mi	0
Jun 7, 2021	EF2	25 km	7.5 mi	0
May 7, 2016	EF2	74 km	8.8 mi	0
Jun 15, 2009	EF2	80 km	4.0 mi	0
Jul 31, 1996	EF2	69 km	5.0 mi	0
Jul 30, 1996	EF2	95 km	0.5 mi	0
Jul 13, 1996	EF2	48 km	12.0 mi	0
May 30, 1996	EF2	96 km	1.0 mi	0
Jun 9, 1990	EF2	89 km	23.0 mi	0
Jun 15, 1988	EF2	21 km	0.5 mi	0
Jun 5, 1988	EF2	9 km	2.0 mi	0
Jun 5, 1988	EF2	11 km	0.5 mi	0
Jul 7, 1987	EF2	72 km	5.0 mi	0
Jul 2, 1987	EF2	19 km	1.0 mi	0
Jun 20, 1987	EF2	32 km	1.0 mi	0

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

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: CAMERON PEAK (208,910 acres, 2020).

Year	Name	Acres Burned	Distance
2020	CAMERON PEAK	208,910	93 km
2020	EAST TROUBLESOME	188,924	96 km
2002	HAYMAN	129,417	83 km
2012	HIGH PARK	90,769	89 km
2020	WILLIAMS FORK	14,679	90 km
2013	BLACK FOREST	11,885	100 km
1996	BUFFALO CREEK	11,690	66 km
2000	BOBCAT	10,444	69 km
2020	CALWOOD	9,836	42 km
2000	HIGH MEADOWS	9,607	68 km
2004	PICNIC ROCK	9,014	92 km
2001	MVD PSFRXASST 4	7,375	79 km
2021	MARSHALL	6,286	21 km
2010	FOURMILE CANYON	5,865	41 km
2002	BIG ELK	4,348	57 km
2021	BIJOU	3,485	87 km
2012	LOWER NORTH FORK FIRE	3,436	57 km
2003	OVERLAND	3,232	42 km
2009	OLD STAGE	3,160	35 km
2011	CRYSTAL FIRE	2,855	78 km

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

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	21°F (-6°C)	0.5 in	Coldest, Driest
February	34°F (1°C)	0.5 in
March	41°F (5°C)	1.4 in
April	48°F (9°C)	2.0 in
May	58°F (14°C)	2.5 in	Wettest
June	68°F (20°C)	1.8 in
July	72°F (22°C)	1.9 in	Warmest
August	71°F (22°C)	1.6 in
September	63°F (17°C)	1.4 in
October	51°F (11°C)	1.1 in
November	38°F (3°C)	1.0 in
December	31°F (-1°C)	0.6 in

Thornton has a seasonal temperature swing of 52°F / from 21°F in January to 72°F in July. Total annual precipitation is 16.3 inches, with May being the wettest month (2.5") and January the driest (0.5").

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