Iowa Memorial Day Week Forecast: Highs Near 87°F Before Cooling to Upper 70s

What changed

The National Weather Service forecast for central Iowa shows a warm front half of the week followed by a noticeable cooldown:

• Memorial Day (Sunday, May 25): High of 85°F
• Tuesday, May 26: High of 87°F
• Wednesday, May 27: High of 86°F
• Thursday, May 28: High of 86°F
• Friday, May 29: High of 79°F
• Saturday, May 30: High of 78°F
• Sunday, May 31: High of 78°F

That's four days in the mid-to-upper 80s, then a step down of about 8°F heading into the first weekend of June.

Why it matters

For corn that's been in the ground a few weeks, those mid-80s daytime highs early in the week could push growing degree day accumulation along nicely. The cooldown to the upper 70s later in the week isn't cold — it's still solid growing weather — but the pace of heat unit accumulation slows a bit. For soybeans going in or just emerging, the entire range stays well within a comfortable window.

The temperature swing itself is worth watching more than any single day. A shift from 87°F to 78°F over a couple of days can change how quickly soil dries out after any rain events, which may matter for late planting or side-dress timing.

What to watch next

• Precipitation forecasts for the same period — temperature tells half the story, and moisture will determine whether fieldwork windows stay open.
• Extended outlooks past June 1 to see if the cooler trend holds or if heat builds back.
• Local conditions can vary from this central Iowa grid point. Check your nearest NWS office forecast for field-level detail.

Source notes

All temperature data from the U.S. National Weather Service API (Des Moines grid point, DMX/73,49). Forecast accessed May 25, 2026.