Iowa 7-Day Forecast: Pleasant Mid-70s Today, Then Heat Builds to 96°F by Sunday

What changed

The NWS Des Moines (DMX) forecast shows a clear two-phase week for central Iowa:

Cooler stretch (Wed–Fri):

• Today (Wednesday): High of 78°F, overnight low 58°F
• Thursday: High of 80°F, overnight low 63°F
• Friday: High of 79°F, overnight low 64°F

Heat ramp (Sat–Tue):

• Saturday: High of 91°F, overnight low 73°F
• Sunday: High of 96°F, overnight low 74°F
• Monday: High of 94°F, overnight low 71°F
• Tuesday night low: 69°F

That's roughly an 18-degree jump in daytime highs from Friday to Sunday, and overnight lows rise by about 16 degrees over the same stretch.

Why it matters

Late July is peak pollination time for much of Iowa's corn crop. Daytime highs in the mid-90s paired with overnight lows in the low-to-mid 70s mean the crop gets limited nighttime cooling. When overnight temps stay above 70°F, corn plants burn more energy on respiration instead of grain fill — something worth watching if your fields are actively silking.

The cooler Wed–Fri window could help fields that are mid-pollination right now. But the weekend heat arrives quickly, so any fields just entering silk may face tougher conditions.

What to watch next

• Duration of the heat: The forecast currently shows 91–96°F highs through at least Monday. Whether that extends further into the following week could affect how much stress accumulates.
• Moisture: This forecast covers temperatures only. Rainfall (or lack of it) alongside 90°F-plus heat changes the stress picture. Check your local NWS office for precipitation outlooks.
• Your fields' stage: Fields actively pollinating during the weekend heat may matter more than those already past silk. Timing varies field to field.

Source notes

All temperatures from the U.S. National Weather Service API, Des Moines (DMX) forecast office grid point (73,49). Forecast issued for the period beginning July 22, 2026.