Iowa 7-Day Forecast: Sustained Heat — Highs 92°F to 96°F Through July 22

What changed

The NWS forecast for central Iowa (Des Moines area) shows a heat build starting today (Wednesday) at 93°F and intensifying through the weekend:

| Day | High | Night Low | |---|---|---| | Wednesday (Jul 15) | 93°F | 72°F | | Thursday (Jul 16) | 92°F | 73°F | | Friday (Jul 17) | 95°F | 76°F | | Saturday (Jul 18) | 96°F | 72°F | | Sunday (Jul 19) | 96°F | 76°F | | Monday (Jul 20) | 95°F | 70°F | | Tuesday (Jul 21) | 87°F | 65°F |

The hottest days are Saturday and Sunday, both forecast at 96°F. Overnight lows stay in the 70s through Sunday night, meaning limited nighttime cooling for crops. Tuesday finally drops to 87°F with a 65°F overnight low — the first real break.

Why it matters

Mid-July heat in the 90s lands right in the window when much of Iowa's corn crop is pollinating or about to pollinate. Sustained highs above 90°F combined with overnight lows that don't dip below the low 70s can increase heat stress on tasseling corn and flowering soybeans. The duration matters here — this isn't a one-day spike. Five days of 92°F or higher with warm nights is a different situation than a quick pop of heat.

How individual fields respond depends on local soil moisture, hybrid selection, and where each field sits in its growth stage. Fields that are already short on moisture could feel this stretch more than those with adequate subsoil reserves.

What to watch next

• Tuesday's forecast: The drop to 87°F on Tuesday is worth watching — if that holds, it signals the end of the run. If it creeps back up, the stress window extends.
• Overnight lows: Nights in the mid-70s limit the crop's ability to recover. Watch whether those lows stay elevated or start falling earlier than forecast.
• Local rainfall: The NWS temperature data here doesn't include precipitation. Check your local NWS office for any rain chances that could moderate the heat or add humidity.
• Crop condition reports: USDA's weekly Crop Progress report (released Mondays) may reflect any heat impact in the following week's condition ratings.

Source notes

All temperature data from the U.S. National Weather Service API, Des Moines (DMX) forecast office grid point. Forecast issued for central Iowa. Local conditions across the state will vary — check your nearest NWS office for site-specific forecasts.