textproduct: Sioux Falls

KEY MESSAGES

- Near to slightly below normal temperatures continue through the end of the week. A couple passing shower and storm chances continue through the end of the week.

- Growing potential for an extended period of heat and humidity beginning Sunday into next week. Heat and humidity could bring very low probabilities for thunderstorms each day.

- A small chance for strong to possibly severe thunderstorms Saturday night into Sunday morning. For now it appears that the cap may hold and the better chances will be north and west.

UPDATE

Issued at 920 PM CDT Wed Jun 24 2026

Forecast remains on track this evening as a few sprinkles are still drifting east-southeast along the Missouri River Valley. This activity is expected to wind down within the next hour or two, with partial clearing and light winds allowing temperatures to fall into the 50s.

Upcoming heat looks to be the primary concern within this forecast period with LREF ensembles continuing to show moderate to high probabilities (50-80+%) of highs exceeding 90F through much of next week. As of right now, the hottest conditions are focused on Sunday/Monday with many areas pushing into the mid to upper 90s and HeatRisk potentially reaching Major levels across much of the forecast area. Plan now to ensure you have access to adequate cooling and hydration next week.

DISCUSSION

Issued at 105 PM CDT Wed Jun 24 2026

A very weak wave in southwest SD will drift through far southeast SD and northern NE late this afternoon into the evening. Model soundings indicate some weak elevated instability with some fairly dry air below this more moist, slightly unstable layer. This may allow a few wind gusts to 40 mph if the showers can develop. Overall this threat should come to an end by about 11 pm.

Thursday should prove to be a very pleasant day with light northerly winds and highs in the 70s.

Upper level troughing begins to develop to the west on Friday which will turn winds more to the southeast and become a bit more gusty. Expecting more widespread high temperatures into the 80s. Overall dry conditions are expected but some elevated weak instability in the mid level could bring some showers to areas west of the James River late Thursday night into Friday morning.

Saturday should prove to be dry as well, although a very weak wave will move north through central SD and could bring some isolated showers to that area. Low level moisture continues to increase ahead of this troughiness to the west, which will increases the instability through the day. However, at this time some strato cumulus is expected to be in place for a good chunk of Saturday which will likely lead to a significant capping inversion.

Saturday night may prove to be our better chance for severe weather, especially west of I-29. For now the better chances look to be northwest of the area, but given the strength of the wave to the west, the strength of the LLJ and the very deep instability, will need to watch out for an MCS to build southeast into the area.

Once this LLJ barrels north on Sunday, the chances for showers and storms should stay mainly north of the area. Sunday will be the first hot day with highs into the 90s and heat indices likely between 95 to 105.

Hot and potentially humid conditions will build into the area through much of next week. Faster southerly flow aloft will remain over parts of central SD, which may allow for an occasional chance for showers and storms as well as cloud cover, so west of I-29 will see a better chance to come up short on high temperatures at times, while near and east of I-29 will likely see the better chances for these hotter conditions with lower chances for showers and storms.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1230 AM CDT Thu Jun 25 2026

VFR conditions and light northwest to variable winds are expected through this period.

FSD WATCHES/WARNINGS/ADVISORIES

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