Historical Weather in Thornton, CO
See 55+ years of weather history for any date in Thornton going back to 1970.
Part of Colorado weather history · Colorado temperature records
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Monthly Climate Averages
Historical temperature and precipitation averages for Thornton, CO, based on 55+ years of weather data.
Temperatures in Fahrenheit. Precipitation and snowfall in inches.
Thornton, CO Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Thornton, CO Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Thornton, CO Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Growing Season & Frost in Thornton, CO
Based on the dates the average overnight low reaches freezing (32°F / 0°C), from 50+ years of NOAA station data.
Thornton, CO also averages 22 days a year at or above 90°F.
Hours of Daylight in Thornton, CO
Day length across the year at 39.9°N latitude. Computed from solar geometry.
Best Time to Visit Thornton, CO
Thornton, CO has no months that meet our "pleasant" threshold — every season has tradeoffs.
Thornton Temperature Records
- Record High: The hottest temperature ever recorded in Thornton, CO is 110°F, set on August 2, 2008.
- Record Low: The coldest temperature ever recorded in Thornton, CO is -26°F, set on December 22, 1990.
- Data Coverage: Based on 43 years of data from NOAA weather station: NORTHGLENN.
All-Time Record High
All-Time Record Low
Monthly Temperature Records in Thornton
| Month | Record High | Record Low |
|---|---|---|
| January | 78°F(1982) | -23°F(2024) |
| February | 83°F(2017) | -24°F(1989) |
| March | 85°F(2017) | -13°F(2002) |
| April | 92°F(1992) | -8°F(1975) |
| May | 101°F(2003) | 19°F(2010) |
| June | 107°F(2012) | 33°F(1998) |
| July | 108°F(2005) | 40°F(1987) |
| August | 110°F(2008) | 37°F(1992) |
| September | 102°F(2020) | 14°F(1985) |
| October | 94°F(1991) | 0°F(1997) |
| November | 85°F(2025) | -14°F(1993) |
| December | 82°F(2025) | -26°F(1990) |