Longmont, CO Weather Forecast
Boulder County, Colorado
Seven-day outlook
37–64°F across the weekThe week runs between 38° and 64°, with today the warmest day of it. The second half leans cooling, and Monday is the coolest day in it. Monday is the wettest day, peaking near 51%. 5 of the 7 days stay dry.
Forecasts come from the National Weather Service's own computer models, and current conditions from the nearest reporting weather station. Both are served through the weather API. A forecast is guidance, not a warning, and anything the Weather Service has actually issued is on the live map.
The written summaries on this page are generated from the forecast data above, not by a meteorologist. Each sentence is a reading of the same numbers you can see, and no forecaster has reviewed them.
About the Longmont forecast
Longmont sits at 40.1699°N, 105.1018°W in Boulder County, Colorado. The forecast above is drawn for that point from the National Weather Service's own computer models: a seven-day outlook, and a finer-grained one covering the next eighteen hours where it reaches, and the radar and alert panels show what the Weather Service has out over the area right now.
- County
- Boulder County
- Coordinates
- 40.1699°N, 105.1018°W
- Population
- 98,630 · 2023 estimate
- Land area
- 29.038 sq mi
Place data from the US Census Bureau. Coordinates are the Census internal point for Longmont, and the forecast is for that location, not for every address inside the city limits, and a large city can have real weather differences from one side to the other.
How well can the network see Longmont?
The nearest Doppler radar is KFTG (Denver, CO), 40 miles to the SE. A WSR-88D's lowest routine scan sits half a degree above horizontal, and the earth curves away beneath it, so by the time that beam reaches Longmont its center is about 2,600 ft above ground. That is comfortably inside the useful range. The lowest scan passes low enough over Longmont to show rotation in the part of a storm where tornadoes actually form. Longmont is closer to its radar than 57% of US cities.
The closest instrument actually measuring the air is KLMO · Longmont/Brand Arpt on the ASOS/AWOS network, 3.2 miles away. Close enough that its readings are, for practical purposes, the conditions in town.
Beam height is the standard 4/3-earth approximation for the 0.5° scan and assumes normal refraction; it is where the center of the beam is, not its edges, and unusual temperature profiles bend it. Radar siting from the NWS WSR-88D network, station positions from the Colorado observing network as of this build.
Forecasts near Longmont
- Mead, CO7 mi
- Frederick, CO8 mi
- Firestone, CO8 mi
- Erie, CO10 mi
- Berthoud, CO11 mi
- Dacono, CO11 mi
- Lafayette, CO12 mi
- Boulder, CO13 mi
Elsewhere in Colorado
DenverColorado SpringsAuroraFort CollinsLakewoodThorntonAll Colorado forecasts →