textproduct: Sioux Falls

KEY MESSAGES

- Light to moderate showers will progress through areas along and south of I-90 as early as this afternoon. Accumulations of a 0.25" to 0.50" of an inch will be possible near and just north of the Missouri River Valley.

- Below normal temperatures expected through Friday, then summer heat returns over the weekend with multiple days of highs in the 90s to possibly low 100s ahead. Heat-related headlines may be needed.

UPDATE

Issued at 849 PM CDT Thu Jul 23 2026

Only minor changes to PoPs and QPF this forecast cycle. Currently a mid-level wave is progressing to the southeast through the region. This is creating light to moderate showers. Severe weather is not anticipated but a few strikes of lightning are still possible. The majority of the activity will be south of I-90 along the Missouri River Valley. However, a few isolated light showers are possible a county or two north of I-90. Shower activity will continue to move southeast through the evening and overnight. A few lingering showers are possible in northwest Iowa Friday morning before they clear the region entirely. Total rainfall of a couple hundredths to a half an inch are expected with the highest amounts along the Missouri River. Isolated pockets of up to an inch are also possible. Low stratus will keep overnight lows on the warm side, in the upper 50s to low 60s. Some patchy fog is possible early Friday morning along water ways and low areas. Fog and stratus should improve through Friday morning, becoming partly to mostly sunny by the afternoon. Enjoy one last day of cooler highs in the upper 70s to 80s.

Saturday another strong high pressure ridge settles over the central CONUS. South to southwest winds will usher in warm and moist air. Highs are expected to climb into the mid 90s to low 100s with the hottest temperatures over central South Dakota. Sunday will be similar if not worse with highs again in the mid 90s to low 100s. Heat index values will be dangerously high, near 100 to 105 with locally higher values possible over central South Dakota. Heat headlines may be necessary, but will hold off this cycle for further refinement of the worst conditions. Please ensure your outdoor plans take into account the very hot weather.

DISCUSSION

Issued at 148 PM CDT Thu Jul 23 2026

An upper level wave and saturation aloft will move through the area later this afternoon through tonight. While some very weak instability is expected aloft, thunder is very unlikely. Saturation aloft is most prominent between I-90 and the Missouri River and with the dry layer in the low levels not excessively dry, some quarter to possibly half inch rainfall amounts are possible over about a 6 hour period.

Friday should generally be dry and mild, maybe a few showers in northwest IA during the morning. Highs remain below normal, but will be a bit higher with most locations climbing into the 80s, coolest in northwest IA.

Hot conditions return for the weekend into early next week. The latest bias corrected data is running about 5 degrees cooler than the model output for Saturday through Monday. Will have to keep an eye on trends as the heat approaches as last weeks warm up the NBM overdid the heat almost every day. This time around there will be a better potential for southwest winds at the surface which generally aids in heating out, so maybe the 3-6 degree warm bias that was seen with the past warm up will be a little less. Long story short, the bias corrected output falls just short of a heat advisory both Saturday and Sunday while the NBM is basically in heat advisory both days.

Convective chances are pretty small through Monday. A slightly stronger wave will drop south on Sunday and bring a small threat for severe storms. The better chance should be north and east of the area. This will be the main time frame to track over the upcoming days.

Tuesday through Thursday should see upper level ridging just west of the area with stronger northwest flow aloft just northeast of the area. This leaves the area in position for above normal temperatures, but possibly not on the excessive side as weak waves will at times allow slightly cooler air to move in. With these weak waves will come periodic chance for showers and thunderstorms but for now confidence in this activity is low.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 629 PM CDT Thu Jul 23 2026

Scattered light to moderate showers and thunderstorms are ongoing at time of issuance. Severe weather is not anticipated but brief heavy downpours are possible. The majority of the activity will remain south of I-90 along the Missouri River Valley. However, isolated sprinkles to light showers are possible a county or two farther north.

The stratus deck is expected to gradually lower through the evening and overnight, eventually resulting in widespread MVFR to possibly IFR conditions. Some patchy fog may further restrict visibility along water ways and low areas. Stratus slowly lifts and clears from west to east through Friday afternoon. Light southerly winds will persist overnight, increasing slightly as the boundary layer begins to mix Friday morning.

FSD WATCHES/WARNINGS/ADVISORIES

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