Longmont, CO Weather & Growing Conditions
This Afternoon
83°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Mostly cloudy. High near 83, with temperatures falling to around 75 in the afternoon. Southwest wind around 5 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 83°F | Chance Showers And Thunderstorms | 5 mph SW | 43% |
| Tonight | 54°F | Chance Showers And Thunderstorms then Partly Cloudy | 2 to 6 mph W | 30% |
| Saturday | 76°F | Partly Sunny then Chance Showers And Thunderstorms | 1 to 6 mph WNW | 67% |
| Saturday Night | 51°F | Chance Showers And Thunderstorms | 3 mph NW | 51% |
| Sunday | 72°F | Showers And Thunderstorms Likely | 1 to 5 mph NE | 55% |
| Sunday Night | 48°F | Chance Rain Showers then Partly Cloudy | 0 to 3 mph NNW | 31% |
| Monday | 73°F | Mostly Sunny | 0 to 5 mph E | 2% |
| Monday Night | 50°F | Mostly Clear | 3 mph NNE | 12% |
| Tuesday | 76°F | Mostly Sunny | 3 mph NE | 10% |
| Tuesday Night | 52°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 3 mph NW | 20% |
| Wednesday | 78°F | Partly Sunny | 5 mph NE | 10% |
| Wednesday Night | 52°F | Slight Chance Rain Showers then Mostly Cloudy | 2 mph WSW | 16% |
| Thursday | 78°F | Mostly Sunny | 1 to 5 mph NNE | 12% |
| Thursday Night | 53°F | Slight Chance Rain Showers then Mostly Cloudy | 3 mph WSW | 23% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Longmont, CO
Last spring frost
May 7
First fall frost
Oct 5
Growing season
151 days
Hardiness zone
5b
Explore more for Longmont, CO: full frost dates · planting calendar · Colorado frost dates
Climate data from the nearest NOAA station, Longmont 2 Ese, Co (1.3 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.