Thornton, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Thornton, a city in Adams County, Colorado.
This Afternoon
56°F
Sunny
Sunny. High near 56, with temperatures falling to around 52 in the afternoon. East northeast wind around 3 mph.
7-day forecast for Thornton
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 56°F | Sunny | 3 mph ENE | 0% |
| Tonight | 35°F | Mostly Clear | 3 mph SSE | 0% |
| Wednesday | 56°F | Mostly Sunny | 2 to 6 mph NNE | 8% |
| Wednesday Night | 36°F | Mostly Cloudy | 5 mph NW | 8% |
| Thursday | 57°F | Sunny | 2 to 6 mph SSE | 0% |
| Thursday Night | 36°F | Partly Cloudy | 3 mph SSW | 1% |
| Friday | 57°F | Mostly Sunny | 5 mph NNE | 6% |
| Friday Night | 36°F | Mostly Clear | 5 mph SW | 6% |
| Saturday | 59°F | Sunny | 5 mph SSE | 0% |
| Saturday Night | 35°F | Mostly Clear | 5 mph SSW | 0% |
| Sunday | 67°F | Sunny | 2 to 6 mph SSW | 0% |
| Sunday Night | 40°F | Mostly Clear | 2 to 6 mph WSW | 0% |
| Monday | 65°F | Sunny | 5 mph SE | 0% |
| Monday Night | 40°F | Partly Cloudy | 5 mph W | 0% |
Forecast source: National Weather Service (api.weather.gov) for Thornton (39.920, -104.941). Updated through the day.
Growing snapshot for Thornton
Last spring frost
May 2
First fall frost
Oct 11
Growing season
160 days
Hardiness zone
6a
More local growing data for Thornton: nearby ZIP 80241 weather · frost dates · planting calendar · Colorado frost dates
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Todd Creek
Twin Lakes
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Westminster
Climate data from the nearest NOAA station, Northglenn, Co (3.8 mi from Thornton). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.