Yankton, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

931
FXUS63 KFSD 250123
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
823 PM CDT Fri Jul 24 2026

.KEY MESSAGES...

- Patchy dense fog is possible tonight, especially for areas of
  northwest Iowa. Visibility may fall to 2 miles or less at
  times. Please use caution and be prepared for rapidly changing
  visibility.

- Heat Advisory in effect area wide for Saturday and Sunday.
  Heat indices running from the upper 90s to around 105.
  Wildfire smoke could be a limiting factor on highs, but for
  now do not believe it will be thick enough to lower
  temperatures too much.

- Isolated severe storms will be possible Saturday evening,
  with the better chances west of I-29.

- While details are uncertain, if storms develop Sunday evening
  into Sunday night, some may be strong to severe with damaging
  winds, isolated large hail and locally heavy rain possible.

- Still a good chance for highs in the 90s next week in most
  locations.

&&

.UPDATE...
Issued at 822 PM CDT Fri Jul 24 2026

Only minor updates to the forecast this period. Southerly winds
remain on the breezy side tonight with gusts of 15-20 mph. Areas
along the Buffalo Ridge in southwest Minnesota may see gusts up to
25 mph. This should work to limit fog potential to water ways and
low areas tonight. Areas of northwest Iowa will have lighter winds
and therefore the better chances (20-50%) for overnight fog
formation. Visibility may decrease to 2 miles or less at times. Be
prepared for rapidly changing visibility. Fog should burn off by mid-
Saturday morning.

Saturday will be hot and humid. Highs will be in the 90s to low 100s
with dew points in the upper 60s to mid 70s. This forecast brings
our Heat Index values into the upper 90s to low 100s. The current
Heat Advisory looks to be in good shape. We will need to watch the
areas along the Missouri River Valley from central South Dakota into
northwest Iowa. Here Heat Index values may cross 105 degrees F. An
upgrade to Extreme Heat Warning may become necessary. These are
very dangerous temperatures. Heat related illnesses can occur
quickly. If you must be outside please dress in loose clothing,
be sure to stay hydrated, and take frequent breaks in an air
conditioned space. Please ensure you know the symptoms of heat
illness and how to treat them. Sunday and Monday will have
similar very hot and humid conditions. Overnight lows will offer
little relief as they remain in the 70s Saturday through Monday
night.

One final note: smoke is expected to flow into the region over the
next few days. With good vertical mixing expected, surface air
quality may begin to degrade. Populations sensitive to pollutants
may need to take precautions.

&&

.DISCUSSION...
Issued at 1259 PM CDT Fri Jul 24 2026

Heat Concerns:

Heat and humidity build back into the area this weekend, with
afternoon and evening heat indices around a 100 or more for most
locations both Saturday and Sunday. Confidence in higher heat
indices for this weekend compared to last weekend is a higher as dew
points look to climb into the lower to mid 70s, which can feel very
oppressive. One limiting factor may be wildfire smoke, but for now
the expectations are that the smoke will be somewhat limited so the
effect on temperatures will likely not be that great. Will have a
heat advisory area wide for the weekend with some potential for
additional heat headlines next week. As confidence grows, a heat
warning may be needed along the James and Missouri River Valleys
Saturday and Sunday where heat indices could climb to around 110.
Most days next week look to have highs in the 90s, so even without
headlines will still be very warm each day.

Thunderstorm concerns:

The latest models continue to hint at isolated thunderstorm
potential Saturday evening and early overnight. For now capping
looks to be a problem, but a weak wave is expected to move into
central SD late afternoon so development may occur to the west of
the Mo River. As the wave shifts east isolated development will
remain possible. Right now the main concerns look to be quarter
sized hail and wind gusts to 65 mph.

Another piece of energy moves into the area on Sunday and should
bring another chance for some isolated severe storms. The better
shear and instability look to reside over southwest MN and this
should be the higher threat for severe storms. Will also need to
keep an eye out for south central SD where the cap could be broken
and an isolated strong to severe storm could develop. Overall there
may be enough dry air in the low levels to really limit the
instability and them main concern would be wind if something could
develop. Confidence for both Saturday and Sunday are fairly low.

Other concerns:

The only other real concern will be the potential for some fog later
tonight into Saturday morning. The better chances will be in
northwest IA, northeast NE and far southeast SD. For now not looking
like widespread dense fog.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 634 PM CDT Fri Jul 24 2026

Mostly MVFR ceilings from roughly Highway 81 and east due to low
stratus. Stratus will continue to erode from west to east through
the evening hours, eventually raising ceilings back to VFR.

Southerly winds remain on the breezy side for most of the region,
especially along the Buffalo Ridge in southwest Minnesota. Sustained
winds of 9-13 kts with gusts 15-22kts are on going. This will work
to limit fog formation in these areas. However, areas of northwest
Iowa where winds will be lighter has a low to medium chance (20-50%)
for fog development. Here ceilings and visibility may briefly fall
to IFR to LIFR. Fog is expected to burn off by mid-Saturday morning.
A warm front is expected to progress through the area Saturday late
morning through the afternoon. As it passes winds will become
variable with gusts around 15 kts.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory from noon Saturday to 8 PM CDT Sunday for
     SDZ038>040-050-052>071.
MN...Heat Advisory from noon Saturday to 8 PM CDT Sunday for MNZ071-
     072-080-081-089-090-097-098.
IA...Heat Advisory from noon Saturday to 8 PM CDT Sunday for
     IAZ001>003-012>014-020>022-031-032.
NE...Heat Advisory from noon Saturday to 8 PM CDT Sunday for NEZ013-
     014.

&&

$$

UPDATE...AJP
DISCUSSION...08
AVIATION...AJP