St. Mary's, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for St. Mary's, a community in Clear Creek County, Colorado.
Today
61°F
Patchy Smoke
Patchy smoke before noon, then patchy smoke and a slight chance of showers and thunderstorms. Mostly sunny. High near 61, with temperatures falling to around 57 in the afternoon. Southwest wind around 9 mph, with gusts as high as 20 mph. Chance of precipitation is 20%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for St. Mary's
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 61°F | Patchy Smoke | 9 mph SW | 24% |
| Tonight | 46°F | Patchy Smoke | 7 to 14 mph SSW | 19% |
| Wednesday | 62°F | Sunny | 13 to 16 mph WNW | 0% |
| Wednesday Night | 45°F | Mostly Clear | 7 to 13 mph W | 0% |
| Thursday | 64°F | Sunny | 14 mph WNW | 2% |
| Thursday Night | 48°F | Clear | 9 to 15 mph W | 1% |
| Friday | 66°F | Sunny | 10 to 14 mph WNW | 1% |
| Friday Night | 50°F | Mostly Clear | 7 to 14 mph SW | 0% |
| Saturday | 66°F | Sunny | 8 to 14 mph NW | 4% |
| Saturday Night | 52°F | Partly Cloudy | 7 to 10 mph WNW | 1% |
| Sunday | 66°F | Mostly Sunny | 10 mph NW | 14% |
| Sunday Night | 52°F | Partly Cloudy | 9 to 13 mph WNW | 10% |
| Monday | 65°F | Slight Chance Rain Showers then Chance Showers And Thunderstorms | 8 to 13 mph WSW | 54% |
| Monday Night | 50°F | Chance Showers And Thunderstorms then Mostly Cloudy | 12 mph WSW | 30% |
Forecast source: National Weather Service (api.weather.gov) for St. Mary's (39.817, -105.647). Updated through the day.
Growing snapshot for St. Mary's
Last spring frost
May 30
First fall frost
Sep 19
Growing season
112 days
Hardiness zone
5b
More local growing data for St. Mary's: nearby ZIP 80436 weather · frost dates · planting calendar · Colorado frost dates
Nearby towns & communities
Blue Valley
Brook Forest
Downieville-Lawson-Dumont
Echo Hills
Empire
Floyd Hill
Georgetown
Pine Valley
Silver Plume
Upper Bear Creek
Upper Witter Gulch
Climate data from the nearest NOAA station, Georgetown, Co (6.1 mi from St. Mary's). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.