textproduct: Sioux Falls

KEY MESSAGES

- An extended stretch of hot temperatures continues through the weekend. Highs in the 90s to 100 degrees expected. The cumulative nature of the heat could lead to some heat health concerns. The good news is dew points will be a bit below seasonal normals, aiding in lower relative humidity.

- Patchy morning fog is possible each morning, but widespread dense fog remains unlikely. Fog will likely be confined to river valleys and nearby areas.

- Minimal precipitation is expected over the next 7 days, with the LREF probability of >0.25" into next Tuesday (July 21st) at 25% or less.

DISCUSSION

Issued at 116 PM CDT Mon Jul 13 2026

Surface high pressure remains locked in place across parts of IA, IL and MO through the middle of the week. Coupled with a strong ridge aloft this will leave the area in a very dry and hot pattern.

The main question marks revolve around the need for any heat headlines. Overall, while most days will see highs in the 90s, the dew points will luckily be below normal, generally in the lower to mid 60s. This aids in two things. One is that morning lows when winds are lighter will drop to around 70 or even into the 60s in many locations, providing some relief from the heat. The other is without the excessive humidity, the bodies natural ability to cool itself is more efficient. With dew points above 70 this bodily process struggles, with dew points in the lower to mid 60s along with some southerly flow the body has a better chance to cool itself.

Also of note is the disparity between the EC ensemble and GFS ensemble output. The GFS is running about 5 degrees hotter than the EC and if the bias corrected output is on to something, the bias corrected data is running about 4-5 degrees cooler than the NBM output which may have too much GFS built in. So, while it will be plenty hot, there is at least a decent chance that highs will continue to come in a couple of degrees less hot than advertised a few days out. Still anticipate widespread highs in the 90s, but maybe low to mid vs. mid to upper in most locations. Central SD will see the best chance to creep up to around 100.

An upper level wave tracks by to the north Thursday into Friday but the effects locally should be minimal. Still hot with dew points in the 60s. One potential would be for the surface front to drop south into the area, bringing lighter winds and possible moisture pooling at the surface which would increase the day time relative humidity.

The next potential for showers and thunderstorms will be Sunday into Monday, but confidence very low right now. Agreement amongst the models is moderate at best. Temperatures will still be on the very warm to hot side of things through next Monday.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1208 PM CDT Mon Jul 13 2026

VFR through the period. Patchy morning fog will be possible, but should be limited to river valleys.

FSD WATCHES/WARNINGS/ADVISORIES

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