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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Today in Thornton Weather HistorySee records, averages, and 55+ years of data for today's date
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Monthly Climate Averages
Historical temperature and precipitation averages for Thornton, CO, based on 55+ years of weather data.
Warmest MonthJulyAvg High: 90°F / Low: 58°F
Coldest MonthJanuaryAvg High: 45°F / Low: 17°F
Jan
45°/ 17°
💧 2.5"
❄️ 1.4"
Feb
47°/ 19°
💧 2.7"
❄️ 1.5"
Mar
56°/ 27°
💧 4.7"
❄️ 1.9"
Apr
63°/ 34°
💧 5.6"
❄️ 1.9"
May
71°/ 43°
💧 6.3"
❄️ 2.0"
Jun
84°/ 53°
💧 5.5"
Jul
90°/ 58°
💧 5.5"
Aug
87°/ 57°
💧 4.8"
Sep
80°/ 48°
💧 5.2"
❄️ 2.0"
Oct
67°/ 36°
💧 4.6"
❄️ 2.1"
Nov
54°/ 26°
💧 3.8"
❄️ 1.8"
Dec
46°/ 18°
💧 3.0"
❄️ 1.6"
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.
Avg high Avg low
Thornton, CO Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Rain (in) Snow (in)
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.
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Best Time to Visit Thornton, CO
Thornton, CO has no months that meet our "pleasant" threshold — every season has tradeoffs.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Pleasant (65-82°F, ≤2.5" rain) Mild Less ideal
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
110°F
August 2, 2008
All-Time Record Low
-26°F
December 22, 1990
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) |
Thornton Snow RecordsSee the top 10 snowiest days ever recorded
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Holiday Weather in Thornton
Weather Analysis & Trends
RecordsHottest Temperatures Ever Recorded in Every US StateAll 50 state record highs ranked, including Colorado.Severe WeatherTornado Season 2026: Forecasts & What to ExpectAn EF5 already, and the peak still ahead.Climate ForecastEl Niño 2026: What Every US Region Should Expect85% likely by late 2026. Region-by-region impact analysis.