Longmont, Colorado Weather
Pikas hayfeeding in granite peaks. Day 76 of spring. Read this microseason across nine climate regions →
Longmont weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast33%—86°50°—
- ThursdayJun 4Overcast——91°51°+5°
- FridayJun 5Mostly Clear——89°56°-2°
- SaturdayJun 6Overcast——96°60°+7°
- SundayJun 7Overcast20%—95°56°-1°
- MondayJun 8Overcast42%—92°63°-3°
- TuesdayJun 9Overcast40%—97°54°+5°
Ozone at AQI 85. AQI flat over the last 6 hours (within ±3 points). Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 85. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
- Present
- AQI 85
- UV peak
- 9.0 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 51
PM × Wind × Precip
PM2.5/PM10 ratio 0.66 with 8 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.66
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- transport
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
The higher the clouds, the finer the weather.
- Moonrise
- 4:54 AM
- Moonset
- 2:01 PM
- In sign
- ♑︎ Capricorn
Pikas hayfeeding in granite peaks
Longmont at a glance
- Today vs. normal: 8°F above the seasonal normal for this latitude
- Last frost: April 17 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Warm-season window is open
As of June 3, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
SPC Convective Outlook
Storm Prediction Center — Longmont
SPC has placed Longmont in the Marginal Risk category for severe thunderstorms today.
- TODAYMRGLMarginal Risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
Isolated severe storms possible. Limited threat for hail or damaging wind.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.