textproduct: Sioux Falls

KEY MESSAGES

- Near to above normal temperatures will continue into the new week with highs mainly in the 80s to mid 90s. Heat indices may approach the upper 90s in spots Monday and Tuesday afternoon.

- After a brief break from severe weather through the daytime Monday, the chances for a few strong to severe storms will increase starting late Monday and again by Tuesday night. Keep up to date with the latest forecast!

UPDATE

Issued at 918 PM CDT Sun Jul 5 2026

A nice summer night is ahead for the area with temperatures falling through the 70s over the next few hours. Despite the clear skies and fairly light winds, increasing southerly flow in the low levels will lead an above average night overall with temperatures dropping into the middle to upper 60s for lows with perhaps a few spots in the lower 70s along the Missouri River Valley. Winds should remain elevated enough overnight to prevent fog from developing for the most part, with the exception being over parts of northwest Iowa near and east of a Ida Grove to Cherokee to Spencer line. This is where winds will generally be the lightest through the night. Any fog should remain patchy with the chance of dense fog less than 25% in these areas. This patchy fog will be possible mainly after 4 am tonight and burn off by 9 Monday morning.

Ridging aloft continues into the day on Monday, so expect a hotter day with highs ranging from the middle 90s west to the middle 80s east. A few spots could see heat index values briefly touch 100 degrees Monday afternoon mainly in south-central South Dakota, but chances for this are low (<20%) and would be short-lived so will hold off on any heat headlines. Either way, be sure to stay hydrated out there especially when doing work outdoors! By Monday afternoon and evening, a surface boundary looks be draped southwest to northeast from the Nebraska panhandle into northeast South Dakota. This will be the focus for showers and storms to develop west and north of the area in the afternoon and early evening. We look to be pretty capped due to a pretty stout warm nose around 700 mb during this time, so the main concern for stronger storms locally will be if anything that develops outside of the area can move in late Monday evening/Monday night and sustain itself. See discussion below for more details on this isolated severe threat.

DISCUSSION

Issued at 136 PM CDT Sun Jul 5 2026

CURRENTS & TONIGHT: A summer-like day continues! Taking a look across the area, quieter conditions persist this afternoon with many areas observing temperatures in the low to upper 80s. This combined with dew points in the upper 60s to low 70s and light winds has led to a picture perfect summer afternoon. With no rain expected in the forecast today mainly due to strengthening ridging, this would be a perfect time to hit the water park/pool and enjoy something cold like ice cream. Otherwise, the seasonable conditions will carry over into the overnight hours as temperatures only decrease into the low to upper 60s for the night.

MONDAY-WEDNESDAY: Looking into the new week, the previously mentioned ridging will begin to flatten by Monday giving way to more quasi-zonal flow aloft. With strengthening mid-level warm air advection (WAA) in place and a return to southerly surface winds, temperatures will continue their gradual increase during the early week leading to daily highs in the mid 80s to mid 90s through Tuesday. This combined with dew points in the upper 60s to low 70s will lead to heat indices in the mid to upper 90s with the most oppressive conditions west of I-29. While this falls just short of heat advisory criteria, make sure to stay hydrated and take frequent breaks if working outdoors! Otherwise, the flow pattern aloft will usher in multiple waves through midweek lead to near-daily chances for a few stronger storms. Starting on Monday, a cold front will stall out roughly from the Black Hills to Northeastern SD. As this front is intersected by an approaching shortwave, scattered showers and thunderstorms will develop with a few potentially becoming severe.

While there are still some questions as to if this developing activity can sustain itself with the limited shear (15-30 kts), there should be at least a low chance (30%-40%) for a few storms to make their way into areas along and south of the U.S. Highway-14 corridor through early Tuesday morning. Nonetheless, if this pulsy activity can maintain its intensity; the main hazards would be up to quarter-sized hail and 60 mph winds gusts. The next chances potentially come from Tuesday night into Wednesday as the stalled boundary lifts towards the ND/SD border and is intersected by a slightly stronger wave generating scattered showers and thunderstorms. While there is still some uncertainty as to how far north the boundary lifts, confidence in our severe weather potential has lower a bit due to the better forcing being just north of us and limited shear/instability. However, we could at least get some pockets of moderate to heavy rainfall out it with PWATs between 1.25" to 1.75" inches and deeper warm cloud depths. While flash flooding is not expect, localized ponding will be possible in any areas that receive prolonged accumulations with this developing activity.

THURSDAY ONWARDS: Heading into the extended period, an active period will continue aloft as quasi-zonal flow continues into the weekend. Multiple waves will progress through the plains leading to at least some smaller chances (<30%) through Saturday. With the ridging expected to strengthen over the western CONUS during the upcoming weekend, we could see the return of oppressive temperatures mainly in the 90s to low 100s as early as Sunday. With heat indices potentially reflecting similar values, make sure to stay hydrated and to monitor your local forecast!

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1238 AM CDT Mon Jul 6 2026

Patchy fog remains possible from about 06.09Z to 06.14Z this morning mainly near and southeast of a KCKP to KSPW line. Dense fog is unlikely, with a 10-30% chance of occurrence. VFR conditions are expected otherwise throughout the day today. Showers and thunderstorms that develop over northern South Dakota may track into the Highway 14 corridor over the last few hours of the period. Winds will be mainly out of the southeast through the period, gusting to around 20 kts near and west of the James River especially in the morning to early afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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