textproduct: Sioux Falls

KEY MESSAGES

- Near to below normal temperatures will dominate the work week with highs in the 50s to lower 60s. - Rain returns by Thursday with a 60-80% probability of greater than 0.25" of rain, and 25% probability of more than 1 inch.

- Nighttime lows may locally dip into the mid-upper 30s through Friday, but more widespread 30s with light winds/clear skies and a better frost potential will be Friday night/Saturday morning.

- Warmer temperatures return through the weekend into early next week with highs back above normal.

UPDATE

Issued at 841 PM CDT Tue Oct 13 2026

Stratus will continue to pivot south and southeast through the overnight hours. Latest guidance pushes this stratus all the way southward towards Highway 20 by daybreak. However, the western edge looks to remain near or just west of the James River valley. Clearing skies could allow overnight lows to fall into the mid-40s through central SD into the MO River valley. At this point the only risk for light frost may be in areas from Chamberlain to Wessington Springs. Further east, clouds should hold temperatures in the 40s.

Weak low lvl flow may really slow down the erosion of stratus on Wednesday, and could potentially lead to lower high temperatures. This may especially be the case in SW Minnesota and adjacent areas of South Dakota.

Everything remains on track for incoming rain late Wednesday night into Thursday. While 00z guidance is just arriving, there seems to be some agreement in 18Z models that a very sharp northwest rain edge will form by mid-morning Thursday, likely near Huron.

DISCUSSION

Issued at 1247 PM CDT Tue Oct 13 2026

Some very weak elevated instability and mid level moisture will move through the area this afternoon and early evening. Very light showers and sprinkles remain possible during this time with no impacts expected.

Winds decrease through the night with temperatures expected to fall back into the low to mid 40s, with a few spots in the upper 30s. The better chance for lows in the 30s will be near highway 14 and in the mid James Valley. For now will not issue a frost advisory as some of the models are hinting that a stratus deck around 1500 feet could develop later tonight which would limit the radiational cooling and frost potential.

Broad warm advection increases on Wednesday night ahead of a wave moving into NE. This forcing continues through a good portion of Thursday, so expect rain late Wednesday night into Thursday. Instability pretty negligible so do not expected any thunderstorms. Rainfall amounts should be highest south of I-90 where a quarter to a half an inch should be more common. The latest Canadian Ens, EC Ens and GEFS show about a 30 to 60 percent chance to exceed a half an inch south of I-90.

Thursday will become breezy with cool temperatures as rain comes to an end in the afternoon and evening. Highs should mostly be in the 50s.

While Saturday morning will be on the cold side, there are still come concerns that southerly return flow could set up early enough Friday night to avoid widespread frost and freeze. Right now, northwest IA and nearby locations appear to see the best chance for light winds late Friday night into Saturday morning and thus the better chance for frost.

Weak ridging and westerly flow aloft will develop Saturday into Sunday, bringing temperatures back to near to above normal during this time. Upper level ridging strengthens early next week and continues through mid week as a large trough deepens over the Rockies. This should support above normal temperatures and mainly dry conditions.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1020 PM CDT Tue Oct 13 2026

MVFR stratus continues to sink southeast late this evening. Short term guidance seems to be congealing on pulling this stratus southward towards the MO river and Highway 20 areas, though how far into NW Iowa is still in question.

A few breaks may form at times in the morning, but MVFR stratus should remain in place into early afternoon with minimal mixing tomorrow.

Eventually stratus will dissipate with an increase in mid-upper clouds ahead of incoming rain very late Wednesday evening.

FSD WATCHES/WARNINGS/ADVISORIES

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