textproduct: Sioux Falls

KEY MESSAGES

- Patchy and locally dense fog near and east of I-29 will lead to visibility below two miles at times through mid morning; widespread dense fog is not expected. Be prepared for quickly changing visibility if traveling.

- Hot and dry conditions return today and continue through next week.

- Daily heat index values remain under 100 degrees for most areas, but the cumulative nature of the heat could lead to increasing potential for heat-related issues.

- Next chances for rain could return by late week. However, severe weather is not expected at this time.

UPDATE

Issued at 305 AM CDT Sat Jul 11 2026

Patchy and locally dense fog has developed this morning, mainly near and east of I-29. Lowest visibility so far has been near US Hwy 71 in northwestern IA, where a couple of sites have briefly dropped to and below a mile. Not currently expecting widespread dense fog, but will monitor trends - especially across northwestern IA where winds are very light to calm. Temperatures this morning are in the upper 50s to the lower 70s with clear skies.

Main story remains the heat with ridging building aloft. Today brings highs in the mid 80s (east) to the mid 90s (west). Dry conditions prevail with light southerly winds. Heat index values remain in the upper 80s to mid 90s with lower humidity across the area. Confidence remains high regarding continued above average temperatures (highs in the 90s to lower 100s) through at least mid next week, but humidity may continue to limit heat index values to below headline criteria. That said, warm overnight lows and extended heat could lead to heat impacts, especially for vulnerable populations or those spending time outdoors.

DISCUSSION

Issued at 1253 PM CDT Fri Jul 10 2026

THIS AFTERNOON and NIGHT: Considerable mid-upper cloud cover from mid-lvl vorticity over eastern Nebraska continues to spreads across the CWA early this afternoon. High resolution guidance keeps this cloud cover spread over the eastern half of the Tri- State area into early evening. Depending on the thickness of this layer, temperatures could be hampered slightly. Further north, we continue to see a compact area of vorticity cross western and southwestern Minnesota with a bit of ACCAS nearby. While some sprinkles may develop with this ACCAS, deeper development remains less likely given weaker instability in the area.

While the high level clouds add some uncertainty, guidance has generally backed off on convective potential later this afternoon and evening. Likely due to a lack of any strong surface convergence and a bit of weak inhibition. I continue to see two areas to watch...one being with the ACCAS field near Watertown, but second along what might be where a weak surface convergence boundary develops by mid-late afternoon from DeSmet to Mitchell and Yankton. Instability in this area will run from 1500-2000 J/KG, but shear is very weak. This results in only pulse severe storms with quarters and very localized 60 mph winds.

Isolated convection may continue over central and west central Minnesota overnight, but further southwest we'll remain quiet with light winds. Some fog may pop up, but widespread dense fog isn't anticipated.

THIS WEEKEND: A quiet weekend is ahead as temperatures begin to slowly rise. Winds will turn to the south or southeast both Saturday and Sunday. High temperatures both days will reach into the upper 80s over MN/IA and into the middle to upper 90s west of I- 29. Heat index values remain below advisory criteria.

NEXT WEEK: A 600 DM ridge will center itself over the Northern Plains for most of next week. This pattern spells two thing...hot and dry. Each day will feature nearly the same identical setup, with a breezy southerly to southeasterly wind and plenty of sunshine. The resulting high temperatures reach the lower to middle 90s along and east of I-29, with temperatures soaring towards the 100 degree mark. ECE/GEFS probabilities show 40+ probabilities of >100 degree highs along the James River valley. The saving grace this week will be the persistent dry air aloft and breezy winds. The resultant mix down each afternoon will drop the dew points towards the 50s and lower 60s. This results in a lower heat index trend, with only isolated spots with a heat index value near 100. While we won't reach advisory criteria in most areas, the cumulative nature of the daily heat and slower fall in overnight lows could still lead to some health related issues.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 610 AM CDT Sat Jul 11 2026

Patchy MVFR to LIFR fog and stratus will continue through mid morning along and east of I-29. Have seen sporadic drops to 1/2SM or less across northwestern IA, but these have been brief and very localized this morning. Have updated TEMPO group for the lower vis at KSUX over the next couple hours.

Once fog and stratus mix out this morning, VFR conditions prevail through the rest of the period. Southerly winds gust to around 20 knots this afternoon toward the James Valley and US Hwy 14 corridor. Winds tonight into early Sunday morning are expected to remain elevated enough to preclude fog development.

FSD WATCHES/WARNINGS/ADVISORIES

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