Longmont, CO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Longmont, a city in Boulder County, Colorado.
Today
79°F
Patchy Smoke
Patchy smoke. Mostly sunny, with a high near 79. East northeast wind around 8 mph.
7-day forecast for Longmont
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 79°F | Patchy Smoke | 8 mph ENE | 13% |
| Tonight | 56°F | Patchy Smoke | 5 to 9 mph NE | 9% |
| Wednesday | 87°F | Patchy Smoke | 3 to 8 mph NE | 1% |
| Wednesday Night | 58°F | Mostly Clear | 2 to 8 mph N | 1% |
| Thursday | 96°F | Sunny | 2 to 8 mph NNW | 0% |
| Thursday Night | 61°F | Mostly Clear | 6 mph N | 1% |
| Friday | 99°F | Sunny | 1 to 7 mph S | 0% |
| Friday Night | 63°F | Mostly Clear | 6 mph SSW | 0% |
| Saturday | 100°F | Sunny | 2 to 7 mph N | 3% |
| Saturday Night | 64°F | Partly Cloudy | 3 to 7 mph WNW | 1% |
| Sunday | 99°F | Sunny | 2 to 8 mph NE | 7% |
| Sunday Night | 67°F | Partly Cloudy | 5 to 8 mph WNW | 5% |
| Monday | 98°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 3 to 10 mph N | 20% |
| Monday Night | 66°F | Slight Chance Showers And Thunderstorms then Mostly Cloudy | 3 to 10 mph W | 16% |
Forecast source: National Weather Service (api.weather.gov) for Longmont (40.170, -105.102). Updated through the day.
Growing snapshot for Longmont
Last spring frost
May 7
First fall frost
Oct 5
Growing season
151 days
Hardiness zone
5b
More local growing data for Longmont: nearby ZIP 80501 weather · frost dates · planting calendar · Colorado frost dates
Nearby towns & communities
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Bark Ranch
Bonanza Mountain Estates
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Crisman
Eldorado Springs
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Gold Hill
Gunbarrel
Hidden Lake
Jamestown
Lafayette
Lazy Acres
Leyner
Louisville
Lyons
Mountain Meadows
Nederland
Niwot
Paragon Estates
Pine Brook Hill
Seven Hills
St. Ann Highlands
Sugarloaf
Sunshine
Superior
Tall Timber
Valmont
Climate data from the nearest NOAA station, Longmont 2 Ese, Co (1.3 mi from Longmont). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.