Thornton, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Thornton, a city in Adams County, Colorado.
Today
79°F
Patchy Smoke
Patchy smoke. Mostly sunny. High near 79, with temperatures falling to around 77 in the afternoon. East northeast wind 6 to 10 mph, with gusts as high as 16 mph.
7-day forecast for Thornton
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 79°F | Patchy Smoke | 6 to 10 mph ENE | 13% |
| Tonight | 57°F | Patchy Smoke | 6 to 10 mph NE | 11% |
| Wednesday | 87°F | Patchy Smoke | 5 to 9 mph NE | 0% |
| Wednesday Night | 61°F | Mostly Clear | 3 to 10 mph S | 2% |
| Thursday | 95°F | Sunny | 3 to 8 mph N | 0% |
| Thursday Night | 64°F | Mostly Clear | 5 to 8 mph S | 2% |
| Friday | 98°F | Sunny | 3 to 8 mph S | 0% |
| Friday Night | 68°F | Mostly Clear | 9 mph S | 0% |
| Saturday | 100°F | Sunny | 5 to 8 mph N | 1% |
| Saturday Night | 68°F | Partly Cloudy | 5 to 8 mph W | 0% |
| Sunday | 99°F | Sunny | 3 to 8 mph ENE | 6% |
| Sunday Night | 69°F | Partly Cloudy | 5 to 9 mph WNW | 4% |
| Monday | 98°F | Sunny then Slight Chance Showers And Thunderstorms | 5 to 10 mph N | 15% |
| Monday Night | 67°F | Partly Cloudy | 3 to 10 mph WNW | 14% |
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
Nearby towns & communities
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Brighton
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Federal Heights
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Northglenn
Peoria
Shaw Heights
Sherrelwood
Strasburg
Todd Creek
Twin Lakes
Welby
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 Aug 4, 2026.