❮
Today Hourly 7 days 30 days September
❯

September 2026 Weather | Longmont, Colorado

Today 9/19
Sunny with a Chance of Thunderstorms
Day 79°
Night 52°
65
Sun 9/20
Sunny with a Chance of Thunderstorms
Day 73°
Night 48°
55
Mon 9/21
Cloudy Weather
Day 75°
Night 48°
5
Tue 9/22
Cloudy Weather
Day 81°
Night 54°
55
Wed 9/23
Cloudy Weather
Day 75°
Night 52°
56
Thu 9/24
Cloudy Weather
Day 81°
Night 54°
55
Fri 9/25
Cloudy Weather
Day 79°
Night 54°
1
Sat 9/26
Cloudy Weather
Day 81°
Night 50°
1
Sun 9/27
Cloudy Weather
Day 77°
Night 52°
1
Mon 9/28
Cloudy Weather
Day 79°
Night 48°
1
Tue 9/29
Stormy Weather
Day 75°
Night 46°
71
Wed 9/30
Sunny with a Chance of Thunderstorms
Day 73°
Night 45°
66

Explore U.S. Weather Trends

❄️ Coldest Cities in the U.S. – Live Temperature Rankings 🔥 Hottest Cities Today – Real-Time Heat Observations ⚠️ Active Weather Alerts – Warnings, Watches & Advisories 🌪️ Windiest Cities – Highest Sustained Wind Speeds 🌫️ Worst Air Quality – Cities with the Highest AQI 🍃 Best Air Quality – Cities with the Lowest AQI