textproduct: Sioux Falls

KEY MESSAGES

- Additional light rain showers are expected overnight, mainly along and north of a Huron to Sioux Falls to Spencer, Iowa line.

- Strong northwest winds continue into Friday morning, with widespread gusts of 30 to 45 mph. Gusts to 50 mph expected overnight in south central South Dakota. Winds taper down Friday afternoon.

- Moderate to high (over 50%) chances of widespread frost early Saturday morning as temperatures fall into the lower and mid 30s. Freeze Watch in effect where confidence is highest in temperatures near and below 32 degrees.

- Dry conditions and warmer temperatures return this weekend into early next week with highs back above normal.

UPDATE

Issued at 840 PM CDT Thu Oct 15 2026

Wind forecast and headlines for tonight/early Friday remains on track. Gusts have tapered a bit across south central SD this evening, should see them increase again toward 45 to 50 mph with the secondary push of CAA and strengthening LLJ. Will have to watch for isolated stronger (40-45 mph) gusts along the Buffalo Ridge overnight, especially if any of the stronger gusts are able to mix down with the wrap around showers. Shower activity should be limited to along and northeast of a Huron to Sioux Falls to Spencer, IA line where better 700mb vorticity is focused. Soundings here are more persistent and deeper with the saturated layer than further south toward the MO River, so did make some changes to pops. Showers should end by the morning commute with minimal accumulations.

Other change to the forecast was to expand the Freeze Watch Saturday morning west toward the James River Valley, where confidence is highest in the potential for near and sub freezing temperatures. Although widespread frost conditions look likely across the area, there is still a little bit of uncertainty in south central SD where southerly lower level flow and WAA may temper some of the efficient radiational cooling, which could keep temperatures a degree or two warmer than forecast and limiting coverage of frost.

DISCUSSION

Issued at 231 PM CDT Thu Oct 15 2026

Rain is ending from northwest to southeast this afternoon as a northern stream upper trough and surface low drag a cold front through the region. At the same time the northern stream upper trough is merging into the southern stream trough responsible for the rain, deepening and strengthening the over all system. Strong winds have begun to develop in response to the tightening SPG and a strong push of CAA. Widespread gusts of 30 to 40 mph are expected. The strongest winds will be located over central South Dakota where gusts to 50 mph are possible. A Wind Advisory is in effect for this area until 4 am Friday morning. The strongest winds will move east overnight with the upper trough but should remain under advisory criteria at 35 to 40 mph. Thanks to the mixy winds and lingering clouds overnight lows tonight will remain in the upper 30s to low 40s.

Early Friday morning there is a chance for additional light, scattered rain showers as moisture wraps around the surface low located over Minnesota. This combined with a second strong push of CAA will result in the LLJ increasing to 50+ kts over east central South Dakota and southwest Minnesota. An area of wind gusts up to 45 mph may be possible in southwest Minnesota. At this time, confidence in winds meeting advisory level criteria are too low to issue a headline. But this will need to be monitored through Friday morning. Winds gradually taper off through Friday afternoon. Highs for Friday will be below average for this time of year (average is low 60s) in the upper 40s to low 50s. Clouds break up through the afternoon and skies will be clear overnight with nearly calm winds. Radiational cooling will allow lows to fall into the mid to low 30s. Areas along and east of I-29 are likely to see temperatures fall to 30 degrees, therefore have issued a Freeze Watch from late Friday night into Saturday morning. Precautions are recommended for sensitive outdoor plants. Areas to the west of I-29 may have the potential for frost development, but confidence was too low at this time to issue a Frost Advisory.

An upper ridge builds into the area for the weekend. Winds turn southerly and WAA will boost our highs back into the upper 50s to mid 60s. Lows will be in the 40s. Dry and warmer than average conditions continue Sunday through the middle part of next week. Highs will warm from the the mid 60s Sunday and Monday into the low 70s Tuesday and Wednesday. Chances for rain return for the second half of next week.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 625 PM CDT Thu Oct 15 2026

Rain continues move east, stretching from KOLU to KSUX to KSPW into central MN at the time of this discussion. Patchy MVFR ceilings near/east of that line push east as well. However, further north and west, additional lower VFR stratus is expected to lower into MVFR conditions overnight. Wrap-around showers will impact portions of the area late this evening and overnight, but should stay north of a KHON to KFSD to KSLB line. Ceilings improve through the afternoon hours Friday, with VFR conditions for the end of the period and onward.

Winds remain strong out of the northwest overnight, with gusts 25 to 35 knots common. Gusts around 40 knots continue across south central SD. Expect winds and gusts to taper down slowly during the morning hours, with gusts around 20 knots into the afternoon and early evening.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Freeze Watch from late Friday night through Saturday morning for SDZ039-040-054>056-060>062-065>071. Wind Advisory until 4 AM CDT Friday for SDZ050-057-063. Wind Advisory until midnight CDT tonight for SDZ052-058-064. MN...Freeze Watch from late Friday night through Saturday morning for MNZ071-072-080-081-089-090-097-098. IA...Freeze Watch from late Friday night through Saturday morning for IAZ001>003-012>014-020>022-031-032. NE...Freeze Watch from late Friday night through Saturday morning for NEZ013-014.