textproduct: Sioux Falls

KEY MESSAGES

- Heat wave continues through the weekend. Highs in the 90s to around 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. - Very patchy morning fog is possible daily, but widespread dense fog remains unlikely. Fog will likely be confined to river valleys and nearby areas.

- Precipitation very unlikely (less than 10%) through Saturday. Sunday into Monday chances rise to 15-20%, but confidence in timing is very low.

UPDATE

Issued at 816 PM CDT Tue Jul 14 2026

The forecasts remains on track with the quiet and clear conditions continuing into the evening. Similar to the last few nights, breezy southerly winds will continue to decrease with the loss of diurnal heating. With higher dew points and lighter surface winds mainly across northwestern IA, patchy valley fog could develop causing temporary reductions in visibility through mid-morning Wednesday. With this in mind, make sure to slow down on those morning commutes. Otherwise, expect a continuation of the summer heat with the ridging firmly overhead. With the higher dew points continuing to be slightly offset from the warmest temperatures, most areas will likely fall just short of heat advisory criteria (HI>=100) on Wednesday. With highs expected to be mainly in the low to upper 90s, expected heat indices (HI) to mirror these temperatures for most areas. With all this being said, make sure to stay hydrated!

DISCUSSION

Issued at 132 PM CDT Tue Jul 14 2026

Overall trends for above normal temperatures continues for the next several days. For Wednesday and Thursday did lower highs a couple of degrees and increase dew points a couple of degrees given latest trends/bias in the guidance. Basically the GFS is too hot and too low of dew points and that is getting incorporated into the NBM guidance and producing a trackable bias. The overall effects will not be significant as heat risks remain below advisory criteria with afternoon heat indices in the 90s.

Friday looks like it could be the hottest day of the week as a weak front settles south and some enhanced mixing becomes possible as surface winds turn more southwesterly. This should be the day with the better chance for more widespread highs from the mid 90s to 103 or so.

On Saturday, the NBM might be running too high given latest MOS and raw output as well as the bias corrected data. All point to lower temperatures. Still far enough out not highly confident on timing of this weaker boundary. On thing that could happen is the front could stall in the area and produce a little moisture pooling at the surface which would bring higher dew points. Something to watch for.

Still some hints that the upper level ridge will break down just enough Sunday into Monday to allow for some isolated shower and thunderstorm potential. This continues to be a lower confidence scenario, especially in terms of timing.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 605 PM CDT Tue Jul 14 2026

Mainly VFR conditions will continue this TAF period as mostly clear conditions persist this afternoon. Similar to the last few night, southerly surface winds will gradually weaken overnight mainly across northwestern IA leading to a few patchy areas of valley fog. Decided to keep any mention of fog out of KSUX at this time since confidence is low in development that far west. However, we'll have to keep watching as the night progresses. Otherwise, expect surface winds to become more southeasterly and increase by Wednesday with gusts between 15-25 mph expected.

FSD WATCHES/WARNINGS/ADVISORIES

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