Iowa Weather Check: Des Moines Temps Cool to 55°F on May 21
Temperature of about 55°F at KDSM at 18:10 UTC on May 21, 2026
Dewpoint of about 41°F at KDSM at 18:10 UTC on May 21, 2026
Barometric pressure of about 30.2 inches of mercury at KDSM at 18:10 UTC on May 21, 2026
What changed
The National Weather Service observation at KDSM logged a temperature of about 55°F at 18:10 UTC on May 21, 2026. The dewpoint came in at about 41°F at the same time, pointing to relatively dry air. Barometric pressure was about 30.2 inches of mercury.
This is a single-station snapshot — it reflects conditions at Des Moines International Airport, not a statewide average.
Why it matters
Late May is a key window for corn and soybean emergence across Iowa. Soil temperatures and air temperatures in the mid-50s°F range are worth watching because crop development can slow when temps stay below the upper 50s for extended stretches. A 55°F reading on its own is not unusual for a single afternoon observation, but if cooler-than-normal conditions persist, it could affect the pace of early-season crop growth.
The low dewpoint (about 41°F) suggests dry air was in place, which may matter for evaporation rates and surface moisture conditions.
What to watch next
- Multi-day temperature trends: One cool reading is routine; several days of below-normal temps could slow emergence. Check your local forecasts and soil temperature monitors.
- Upcoming precipitation: Dry air at the surface could signal a stretch without rain. Local soil moisture conditions are worth keeping an eye on.
- Statewide crop progress: USDA's weekly Crop Progress report (typically released Mondays) will show how Iowa corn and soybean emergence compares to the five-year average.
Source notes
- Temperature, dewpoint, and pressure data from the U.S. National Weather Service API — KDSM station latest observation (source).
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