South Dakota 7-Day Forecast: Highs Jump From 60°F to 94°F by Memorial Day

What changed

The National Weather Service grid-point forecast (Aberdeen, SD) lays out a sharp temperature ramp this week:

• Friday (May 22): High of 60°F
• Friday Night: Low dropping to 40°F
• Sunday Night: Low of 52°F — overnight temps already climbing
• Memorial Day (May 25): High of 94°F
• Tuesday (May 26): High of 93°F
• Wednesday (May 27): High of 83°F
• Thursday (May 28): High of 80°F

That's a 34-degree swing from Friday's high to Monday's high, with overnight lows rising from 40°F to the low 50s over the same stretch.

Why it matters

A jump from 60°F to the low-to-mid 90s in a few days is a lot for late-May South Dakota. For corn and soybeans that are recently emerged or still going in the ground, this kind of heat could:

• Speed up GDU accumulation. Warmer nights in the 50s combined with daytime highs in the 80s and 90s will stack growing degree units quickly.
• Increase moisture demand. Fields that were comfortable at 60°F will dry out faster under 90°F-plus heat, especially if rainfall stays limited.
• Test young seedlings. Newly emerged corn and soybeans can handle heat, but a sudden spike may matter more if soil moisture is already thin in parts of the state.

The midweek pullback to the low 80s by Wednesday and Thursday offers some relief, but the first few days of the week look genuinely hot for this point in the season.

What to watch next

• Updated NWS forecasts later this week — these numbers can shift, especially the peak highs.
• Rainfall outlooks — heat without rain is a different story than heat with timely moisture. Check your local NWS office for precipitation chances.
• Crop condition reports — USDA's weekly Crop Progress report (typically out Monday afternoons) may reflect planting pace and early emergence across SD.

Source notes

All temperature data from the U.S. National Weather Service API, Aberdeen SD grid point (NWS API link). Forecast as of May 25, 2026.