textproduct: Sioux Falls

KEY MESSAGES

- Hot conditions continue into the weekend. Highs in the 90s to around 100 expected. Friday appears to be the hottest day. Dew points remain a bit below seasonal normals, aiding in lower relative humidity. However, the cumulative nature of the heat could lead to some heat impacts. - Very patchy morning fog is possible daily, but widespread dense fog remains unlikely. Fog will likely be confined to river valleys and nearby areas, but could reduce visibility below two miles at times.

- Precipitation is very unlikely (less than 10%) through Saturday night. Sunday into Monday chances rise to 15-25%, with some growing confidence the better chances will be Sunday evening into the night.

DISCUSSION

Issued at 150 PM CDT Wed Jul 15 2026

Very little change to the forecast for the next several days as upper level ridging continues to produce hot temperatures. So far with dew points mostly in the 60s, heat indices and heat risks have remained a bit muted, but if you need to be outdoors take any necessary heat precautions as it is still in the 90s. With a bit stronger southerly wind tonight and Thursday night overnight lows will trend warmer, likely only falling to 70 to 75 degrees. Fog chances may be lower as well because of the wind.

Friday will see a front approach from the north as northwest flow aloft increases a bit, which should aid in bringing surface winds around to a bit more southwesterly direction. This should help with deeper mixing and likely higher temperatures, with most locations climbing to 95 to 102 degrees, warmest in central SD. Right now Friday appears to see the best chance for a heat headline. This front will slide into the area Friday night into Saturday morning, but is not expected to produce any showers or storms.

A bit better dip in upper level flow moves through Sunday night which looks like the best chance for isolated to scattered showers and storms. For now Sunday appears to be on the dry side with any shower and storm chances moving in Sunday night. There some hints of elevated moisture and very weak instability on Sunday morning around 10-15 kft which could produce some weak ACCAS showers, but confidence very low on this.

Stronger west and northwest flow aloft continues along the Canadian border into northern MN early next week, possibly becoming a bit more pronounced by Monday night into Wednesday. This should support temperatures back to around normal or maybe a touch below. This may bring some patchy showers and storms to the area as well.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1147 AM CDT Wed Jul 15 2026

VFR through the period. Some 3-6 kft diurnally driven cumulus is expected through about sunset. Patchy fog will again be possible but impacts will be minimal.

CLIMATE

Issued at 252 AM CDT Wed Jul 15 2026

Daily record highs for our four climate sites (Huron, Mitchell, Sioux Falls, and Sioux City) are all squarely into the 100-110+ range through the next week, so not expecting any record highs. Record warm lows are in the upper 70s to lower 80s so again, not expected any records here either at this time.

Looking at the duration of the heat via consecutive 90+ degree days, we may approach the Top 10 list for some locations if 90+ degree highs remain in place through early next week. With heat looking to break into the 80s mid to late next week, we will not be anywhere close to the longest streak of 90s for any climate sites.

Longest streak (year of occurrence): - HON: 23 days (1941, 1974) - MHE: 27 days (1936) - FSD: 19 days (1910) - SUX: 27 days (1936)

To break into the top 10 list, we'd have to match or exceed the following streaks for each climate sites:

- HON: 11 days; occurred 6 times, last in 1991 - MHE: 15 days; occurred 3 times, last in 1964 - FSD: 11 days; occurred 4 times, last in 1989 - SUX: 12 days; occurred 5 times, last in 1955

Current (through Tuesday, 7/13) streaks are: - HON: 4 days; streak began July 10 - MHE: 4 days; streak began July 10 - FSD: 2 days; streak began July 12 - SUX: 0 days; last hit 90+ on July 8

FSD WATCHES/WARNINGS/ADVISORIES

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