St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

650
FXUS63 KEAX 262014
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
314 PM CDT Wed Aug 26 2026

.KEY MESSAGES...

- Temperatures will be closer to normal through Friday with highs in
  the 80s and lows in the 60s.

- Hot and humid conditions build into the area this weekend and
  then intensify through the first half of next week.

&&

.DISCUSSION...
Issued at 300 PM CDT Wed Aug 26 2026

Water vapor imagery with 500mb heights plotted shows a trough moving
through the Great Lakes area. A secondary trailing shortwave was
evident moving through the IA/IL area. At the surface, a cold front
moved through earlier, shifting winds to the north and allowing
cooler/drier dewpoints to build south into the area as high pressure
moves into the Northern and Central Plains. This high pressure will
be the main feature influencing our weather through the end of
the week. With that high moving through the region Thursday,
highs look to be in the low to mid 80s across the area. But
dewpoints settling into the lower 60s will be noticeably drier.
That high pressure area shifts east by Friday, starting a
warming trend as low-level flow trends southerly again. This
should lead to highs a few degrees warmer than Thursday.
Moisture will lag the increase in temperatures so we`ll still
see lower humidity levels Friday.

For the weekend and into next week, the upper ridge that was
centered over the western half of the US will shift east, aiding the
warmup, and persistent southerly flow will allow for greater
moisture to return into the area. High temperatures will climb
back into the 90s with this pattern with dewpoints climbing back
into the middle to upper 60s Saturday, and potentially into the
lower 70s by Sunday. For now, Monday looks like the hottest day
of this forecast with highs climbing into the middle and upper
90s. The GFS is a strong warm outlier here and looking at a violin
plot of max temperatures in the forecast area for Monday, it
clearly shows the GFS is a very warm outlier and well above the
90th percentile of guidance. Our forecast is closer to the 75th
percentile. With the increasing dewpoints factored in, our heat
index values climb back into the 100-105 range for most
locations Sunday and Monday, with the brunt of the heat focused
south of the Missouri river Tuesday and Wednesday. We`ll need to
monitor this period for possible heat headlines as a small
increase in moisture will lead to more widespread heat index
values near 105. In fact, by early next week, there is a greater
than 75% chance for seeing at least major HeatRisk and low
probabilities of extreme HeatRisk.

Regarding precipitation chances through the forecast, they look
small and mainly across far northern Missouri, along the periphery
of the upper ridge for next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 154 PM CDT Wed Aug 26 2026

VFR conditions are expected through the forecast at all sites,
with the exception of STJ, where this a low potential for fog
tomorrow morning. Drier is moving into the region with high
pressure settling southward. That drier air will help mitigate
fog potential tonight but with temperatures falling into the
lower 60s in NW MO, there may be some river valley fog at the
STJ terminal.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...CDB
AVIATION...CDB