textproduct: Sioux Falls

KEY MESSAGES

- Heat indices may approach the upper 90s Monday and Tuesday afternoon.

- Isolated strong to severe storms will be possible Monday evening in areas along and north of I-90. 60 mph winds will be the greatest risks.

- Scattered severe storms capable of quarter size hail and 60 mph winds will again be possible late Tuesday afternoon into early Wednesday.

- Temperatures rise towards the middle 90s to 100 degree mark by next weekend.

UPDATE

Issued at 314 AM CDT Mon Jul 6 2026

No major updates to the current forecast this morning. There remains potential or patchy fog or low stratus this morning and higher dewpoints move back northward.

06Z model guidance continues to suggest isolated to scattered storms form along a frontal boundary from the Fargo area to Pierre and Alliance. The generally weak flow will keep this activity from rapidly advancing, with more storm motion dictated by cold pool formation. 700 mb temperatures remain very warm (+13C) along and north of I-90 this evening, so any strong storm may struggle to drift southward into the warmer air and should dissipate by I-90. Strong winds remain the primary risk with all of the activity later this evening.

The initial threat for convection will be focused along a stalled frontal boundary through central and northeastern South Dakota Tuesday afternoon. Slow eastward trajectories may delay the arrival of one or more clusters of convection from arriving until the late evening. This combined with very warm 700 mb temperatures once again could limit the southeastward track of any storm clusters as well.

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 /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 547 AM CDT Mon Jul 6 2026

VFR conditions continue this morning. Patchy MVFR fog has been observed in areas where we've cooled into the lower 60s. This fog should dissipate quickly this morning, with lingering high level clouds into mid-day.

A scattered diurnal CU field is likely as winds turn more southerly and gust towards 20 knots this afternoon. We'll turn our eye to the north and watch for convection to drift southward late in the evening and overnight. Areas near Highway 14 have the greatest potential to see this convection, so will include a Prob30 group in Huron.

Elsewhere, expect a broken mid-high level cloud layer due to nearby convection.

FSD WATCHES/WARNINGS/ADVISORIES

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