textproduct: Sioux Falls

KEY MESSAGES

- Warmer and more humid air returns Friday through the weekend with moderate (40-60%) chances for storms late Friday into Friday night.

- Periodic shower and storm chances continue this weekend into early next week. Confidence on any details is low.

- Temperatures will be above normal this weekend into the middle of next week. Highs likely in the 90s Saturday and possibly Sunday.

DISCUSSION

Issued at 108 PM CDT Wed Aug 26 2026

Surface high pressure remains in place through Thursday resulting in quiet weather across the area. Lows in the 50s tonight with highs on Thursday in the lower to mid 80s.

Elevated moisture moves in around the 700-800 mb layer late Thursday night into Friday morning. This could result in spotty showers and isolated thunderstorms. Shear is weak and CAPE values running about 500-1000 J/kg. Very defendant upon this small layer of moisture however, so confidence is low for now.

Southerly flow become established at the surface on Friday with gusts around 25 to 30 mph likely. With south to southeast flow at the surface any instability that develops through the day will likely remain capped, however with some potential for a wave to move through on Friday afternoon this capping could weaken and allow a few thunderstorms to develop. With moderate shear and 1000-1500 J/kg CAPE, an isolated severe storm will be possible. A secondary wave and slightly deeper instability on Friday night may lead to additional shower and thunderstorm chances with additional severe weather threats.

Temperatures warm across the area on Saturday as the wave moves by to the north. Even with stronger west southwest flow aloft and decent mid level warm advection, weak mid to upper level ridging should suppress any convective activity. Highs should climb into the 90s near and west of I-90.

Sunday may be a day to keep an eye on we a wave tracks by along the Canadian border and a weaker sub tropical like wave drifts northeast into the area. With another day expected to climb into the 90s and some weak forcing aloft, we could see a few storms develop. For now confidence is too low to include in the forecast.

Southwest flow aloft remains in place through the middle of next week and the next wave of interest has some agreement and may arrive Monday night into Tuesday. Otherwise temperatures will remain above normal Monday int Wednesday.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1157 AM CDT Wed Aug 26 2026

VFR through the period. Northwest winds will gust around 25 mph at times this afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None. IA...None. NE...None.