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 late tonight/Thursday with a 70-90+% probability of greater than 0.25" of rain near and south of I-90, 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, especially along and east of I-29.

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

UPDATE

Issued at 420 AM CDT Wed Oct 14 2026

Stratus continues to slowly sink southward into the forecast area early this morning, holding temperatures in the 40s for all except our far southwest near the Missouri River Valley. With a very light northeast flow within the cloud layer which extends beyond the Minnesota/Canada border, it may be tough to really erode the clouds today, especially across southwest Minnesota and nearby areas (I-29 into far northwest Iowa). This could hold high temps in the middle to even lower 50s in these areas, while western and southern parts of the forecast area climb closer to 60F.

Rain is on track to spread northeast into the region through tonight, becoming most widespread and persistent along/south of I-90 late tonight through midday Thursday. Subtle instability could support a few thunderstorms which could enhance rainfall amounts through portions of the Missouri River Valley into northwest Iowa, and added a mention of thunder to these areas as NBM thunder chances were largely sub-mentionable.

While confidence in amounts greater than 0.25 to 0.50 inch in our southern areas is fairly high, there is still plenty of uncertainty in 24-hour rainfall totals. Latest NBM is showing as much as 0.50 to 0.75 ensemble spread between the 25th and 75th percentiles, with 90th percentile amounts as high as 1.50 to 2 inches in some areas. Rainfall rates are not expected to be excessive though, with a fairly steady moderate rain not expected to have a significant impact on rivers. However, with leaves starting to fall, homeowners may want to check gutters and downspouts to ensure they are clear, while also ensuring storm drains are clear of leaves.

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.