421
FXUS63 KFSD 152321
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
621 PM CDT Wed Jul 15 2026

.KEY MESSAGES...

- Hot conditions continue into the weekend. Highs in the 90s to
  around 100 expected. Friday appears to be the hottest day.
  Dew points remain a bit below seasonal normals, aiding in
  lower relative humidity. However, the cumulative nature of the
  heat could lead to some heat impacts.

- Very patchy morning fog is possible daily, but widespread
  dense fog remains unlikely. Fog will likely be confined to
  river valleys and nearby areas, but could reduce visibility
  below two miles at times.

- Precipitation is very unlikely (less than 10%) through
  Saturday night. Sunday into Monday chances rise to 15-25%,
  with some growing confidence the better chances will be Sunday
  evening into the night.

&&

.DISCUSSION...
Issued at 150 PM CDT Wed Jul 15 2026

Very little change to the forecast for the next several days as
upper level ridging continues to produce hot temperatures. So far
with dew points mostly in the 60s, heat indices and heat risks have
remained a bit muted, but if you need to be outdoors take any
necessary heat precautions as it is still in the 90s. With a bit
stronger southerly wind tonight and Thursday night overnight lows
will trend warmer, likely only falling to 70 to 75 degrees. Fog
chances may be lower as well because of the wind.

Friday will see a front approach from the north as northwest flow
aloft increases a bit, which should aid in bringing surface winds
around to a bit more southwesterly direction. This should help with
deeper mixing and likely higher temperatures, with most locations
climbing to 95 to 102 degrees, warmest in central SD. Right now
Friday appears to see the best chance for a heat headline. This
front will slide into the area Friday night into Saturday morning,
but is not expected to produce any showers or storms.

A bit better dip in upper level flow moves through Sunday night
which looks like the best chance for isolated to scattered showers
and storms. For now Sunday appears to be on the dry side with any
shower and storm chances moving in Sunday night. There some hints of
elevated moisture and very weak instability on Sunday morning around
10-15 kft which could produce some weak ACCAS showers, but
confidence very low on this.

Stronger west and northwest flow aloft continues along the Canadian
border into northern MN early next week, possibly becoming a bit
more pronounced by Monday night into Wednesday. This should support
temperatures back to around normal or maybe a touch below. This may
bring some patchy showers and storms to the area as well.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 620 PM CDT Wed Jul 15 2026

VFR conditions are expected for the TAF period. A CU field that has
developed this afternoon will dissipate as diurnal heating fades
this evening. Winds will go light and variable overnight, leading to
the potential for some patchy fog across the area. Winds will pick
up out of the south tomorrow with another CU field expected to
develop. These conditions will finish out the TAF period.

&&

.CLIMATE...
Issued at 252 AM CDT Wed Jul 15 2026

Daily record highs for our four climate sites (Huron, Mitchell,
Sioux Falls, and Sioux City) are all squarely into the 100-110+
range through the next week, so not expecting any record highs.
Record warm lows are in the upper 70s to lower 80s so again, not
expected any records here either at this time.

Looking at the duration of the heat via consecutive 90+ degree days,
we may approach the Top 10 list for some locations if 90+ degree
highs remain in place through early next week. With heat looking to
break into the 80s mid to late next week, we will not be anywhere
close to the longest streak of 90s for any climate sites.

Longest streak (year of occurrence):
- HON: 23 days (1941, 1974)
- MHE: 27 days (1936)
- FSD: 19 days (1910)
- SUX: 27 days (1936)

To break into the top 10 list, we`d have to match or exceed the
following streaks for each climate sites:

- HON: 11 days; occurred 6 times, last in 1991
- MHE: 15 days; occurred 3 times, last in 1964
- FSD: 11 days; occurred 4 times, last in 1989
- SUX: 12 days; occurred 5 times, last in 1955

Current (through Tuesday, 7/13) streaks are:
- HON: 4 days; streak began July 10
- MHE: 4 days; streak began July 10
- FSD: 2 days; streak began July 12
- SUX: 0 days; last hit 90+ on July 8

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...08
AVIATION...Meyers
CLIMATE...SG