Columbia, IL Weather Forecast
Monroe County, Illinois
Seven-day outlook
43–81°F across the weekThe week runs between 55° and 81°, with today the warmest day of it. There is no real trend across it: one day looks much like the next. Tuesday is the wettest day, peaking near 52%. 3 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 Columbia forecast
Columbia sits at 38.4581°N, 90.2160°W in Monroe County, Illinois. 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
- Monroe County
- Coordinates
- 38.4581°N, 90.2160°W
- Population
- 10,933 · 2023 estimate
- Land area
- 10.55 sq mi
Place data from the US Census Bureau. Coordinates are the Census internal point for Columbia, 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 Columbia?
The nearest Doppler radar is KLSX (St. Louis, MO), 30 miles to the WNW. 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 Columbia its center is about 1,800 ft above ground. That is about as close as radar coverage gets in the United States: the lowest scan is still near the ground when it reaches Columbia, so low-level rotation and the leading edge of a gust front show up on it. Columbia is closer to its radar than 70% of US cities.
The closest instrument actually measuring the air is KCPS · St Louis/Downtown Arpt on the ASOS/AWOS network, 8.4 miles away. Near enough to be representative on most days, though a summer thunderstorm can soak one and miss the other entirely.
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 Illinois observing network as of this build.
Forecasts near Columbia
- Dupo, IL4 mi
- Millstadt, IL7 mi
- Green Park, MO8 mi
- Cahokia Heights, IL9 mi
- Arnold, MO9 mi
- Waterloo, IL9 mi
- Shrewsbury, MO11 mi
- Crestwood, MO11 mi
Elsewhere in Illinois
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