Longmont, Colorado Weather
Monsoon storms drench the south. Day 14 of summer. Read this microseason across nine climate regions →
Longmont weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Overcast——92°57°—
- SundayJul 5Overcast——96°57°+4°
- MondayJul 6Overcast——97°59°+1°
- TuesdayJul 7Light Drizzle38%—101°59°+4°
- WednesdayJul 8Light Drizzle52%—98°61°-3°
- ThursdayJul 9Overcast30%—102°55°+4°
- FridayJul 10Overcast13%—103°64°+1°
AQI 47 (Good), driven by Ozone. Ozone at AQI 100 now. With UV 6.8 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 64 around 1 PM.
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 100 now. With UV 6.8 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 64 around 1 PM.
- Present
- AQI 100
- UV peak
- 6.8 at 1 PM
- Sky at peak
- partly cloudy
- Projected peak
- AQI 64
PM × Wind × Precip
PM2.5 at 13.2 µg/m³ (AQI 59) with a 0.83 fine-to-coarse ratio and 2 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.83
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 10:56 PM
- Moonset
- 10:09 AM
- In sign
- ♓︎ Pisces
Monsoon storms drench the south
Longmont at a glance
- Today vs. normal: 10°F above the seasonal normal for this latitude
- Last frost: April 17 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP codes: 80501, 80503, 80504
16-Day Forecast — Longmont
- Sat93°57°5%
- Sun96°57°3%
- Mon97°59°5%
- Tue101°59°38%
- Wed98°61°52%
- Thu102°55°30%
- Fri103°64°13%
- Sat100°57°5%
- Sun109°64°4%
- Mon109°66°17%
- Tue108°69°17%
- Wed95°63°49%
- Thu88°64°49%
- Fri93°62°48%
- Sat96°64°42%
- Sun98°68°39%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Longmont
Right now in the garden
Peak growing season
As of July 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
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 3TSTMGeneral Thunderstorms
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.
ZIP codes in Longmont
- 80501
- 80503
- 80504