textproduct: Sioux Falls

KEY MESSAGES

- The next better chance for showers and storms is Sunday night (50- 70%). Locally heavy rain and isolated severe storms are possible.

- Otherwise most days through next week will see highs in the 80s and lows in the upper 50s to lower 60s.

DISCUSSION

Issued at 142 PM CDT Sat Aug 22 2026

A quiet night is ahead as high pressure drifts east. Southerly flow will develop in central SD later tonight and become more established across the area through Sunday. The light winds will allow temperatures to fall into the lower 50s, especially east of I- 29.

The upper level wave responsible for the low level winds turning southerly will move into central SD tomorrow morning, and eastward and southeast from there through the day. With fairly stout low to mid level dry air, mainly an increase in cloud cover is expected through the morning. The exception will be south central SD where enough moisture may allow for 500-1000 J/kg of elevated CAPE, which will support some spotty showers and thunderstorms. Severe weather is not expected.

Lift will gradually increase through the day into Sunday night, when a moderately stronger LLJ focuses on the area. Given fairly weak shear and CAPE values generally under 1000 J/kg, severe weather looks unlikely. However with a freezing level around 13 kft, locally heavy rain will be possible. Not much agreement on the location of the heavier rain with the models pretty inconsistently placing the mid level wave across the area. Some hints that the LLJ will focus somewhere on the SD side, but confidence is low.

This wave moves out of the area on Monday but another weaker wave moves by to the north on Monday night and brings a small increase in warm air advection, which could spark a few showers and thunderstorms.

Mainly northwest flow aloft continues Tuesday into next weekend. This will bring periodic small chances for showers and thunderstorms throughout the week with little agreement on exactly when. Otherwise lows should mainly be from the mid 50s to mid 60s with highs in the 80s.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1222 PM CDT Sat Aug 22 2026

VFR through the period. Spotty showers and very isolated thunderstorms will be possible in south central SD late tonight into Sunday morning. Some patchy low land fog will be possible late tongiht into Sunday morning.

FSD WATCHES/WARNINGS/ADVISORIES

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