textproduct: Sioux Falls

KEY MESSAGES

- Heat wave continues through the weekend. Highs in the 90s to 100 degrees expected. Dew points remain a bit below seasonal normals, aiding in lower relative humidity. However, cumulative nature of the heat could lead to some heat impacts. - Patchy morning fog is possible daily, 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 probability of > 0.25" into next Tuesday (July 21st) around 25% or less.

UPDATE

Issued at 243 AM CDT Tue Jul 14 2026

No significant changes to the forecast this morning.

Another morning with clear skies, southerly winds, and temperatures in the mid 60s to mid 70s. Patchy fog may again reduce visibility to below two miles in some river valleys; expect reduced visibility to be isolated and brief through roughly 8 AM.

Confidence remains very high in the continued hot, sunny, and dry weather into this weekend. Highs today will be similar to Monday with CAA overhead - upper 80s and 90s. Highs in the 90s to near 100 continue into the weekend with heat indices similar to air temperatures due to relatively low humidity. Southerly wind gusts each afternoon around 20-25 mph. Continue to limit heat and sun exposure to reduce your risk of heat illness.

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 /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 559 AM CDT Tue Jul 14 2026

Some patchy MVFR and lower fog continues through about 13z for southwestern MN and northwestern IA. Otherwise, VFR conditions through most of the period with clear skies. Fog may develop again Wednesday morning along/near river valleys east of I-29.

Southerly wind gusts around 20 knots, slightly higher across south central SD. Gusts taper down tonight, with winds turning light and variable east of I-29 late.

FSD WATCHES/WARNINGS/ADVISORIES

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