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.
This Afternoon
53°F
Showers And Thunderstorms
Showers and thunderstorms. Mostly cloudy. High near 53, with temperatures falling to around 45 in the afternoon. West southwest wind around 6 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for St. Mary's
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 53°F | Showers And Thunderstorms | 6 mph WSW | 77% |
| Tonight | 40°F | Chance Showers And Thunderstorms then Partly Cloudy | 7 to 13 mph W | 33% |
| Saturday | 50°F | Slight Chance Rain Showers then Chance Showers And Thunderstorms | 8 to 12 mph WSW | 70% |
| Saturday Night | 36°F | Chance Showers And Thunderstorms then Slight Chance Showers And Thunderstorms | 7 to 10 mph W | 27% |
| Sunday | 46°F | Slight Chance Rain And Snow Showers then Slight Chance Showers And Thunderstorms | 10 to 15 mph WNW | 18% |
| Sunday Night | 34°F | Mostly Clear | 6 to 9 mph W | 6% |
| Monday | 50°F | Sunny | 8 mph WNW | 4% |
| Monday Night | 37°F | Partly Cloudy | 5 to 8 mph S | 3% |
| Tuesday | 52°F | Partly Sunny then Showers And Thunderstorms Likely | 8 mph NW | 55% |
| Tuesday Night | 39°F | Chance Showers And Thunderstorms then Mostly Cloudy | 6 to 9 mph SW | 33% |
| Wednesday | 50°F | Partly Sunny then Chance Showers And Thunderstorms | 9 mph W | 46% |
| Wednesday Night | 39°F | Slight Chance Rain Showers then Mostly Cloudy | 7 mph W | 23% |
| Thursday | 50°F | Partly Sunny then Chance Showers And Thunderstorms | 8 mph E | 35% |
| Thursday Night | 40°F | Chance Rain Showers then Mostly Cloudy | 7 mph SSW | 31% |
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 Sep 18, 2026.