Thornton, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Thornton, a city in Adams County, Colorado.
Today
76°F
Mostly Sunny then Chance Showers And Thunderstorms
A chance of showers and thunderstorms between noon and 3pm, then showers and thunderstorms likely. Mostly sunny. High near 76, with temperatures falling to around 69 in the afternoon. Northeast wind 2 to 9 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for Thornton
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 76°F | Mostly Sunny then Chance Showers And Thunderstorms | 2 to 9 mph NE | 60% |
| Tonight | 52°F | Chance Showers And Thunderstorms then Partly Cloudy | 2 to 7 mph SSW | 41% |
| Sunday | 71°F | Partly Sunny then Chance Showers And Thunderstorms | 2 to 8 mph NE | 29% |
| Sunday Night | 51°F | Chance Showers And Thunderstorms then Partly Cloudy | 1 to 7 mph N | 30% |
| Monday | 73°F | Mostly Sunny | 1 to 9 mph NE | 2% |
| Monday Night | 51°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 2 to 9 mph SSE | 24% |
| Tuesday | 76°F | Mostly Sunny | 2 to 6 mph ESE | 6% |
| Tuesday Night | 54°F | Partly Cloudy | 6 mph SW | 14% |
| Wednesday | 78°F | Mostly Sunny | 6 mph NNE | 8% |
| Wednesday Night | 54°F | Mostly Cloudy | 2 to 6 mph SW | 11% |
| Thursday | 79°F | Mostly Sunny | 2 to 8 mph S | 6% |
| Thursday Night | 56°F | Partly Cloudy | 2 to 8 mph S | 13% |
| Friday | 80°F | Mostly Sunny | 2 to 7 mph S | 11% |
| Friday Night | 56°F | Slight Chance Rain Showers then Partly Cloudy | 3 to 7 mph S | 15% |
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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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 Sep 19, 2026.