Decatur, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

732
FXUS63 KILX 200709
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
209 AM CDT Thu Aug 20 2026

.KEY MESSAGES...

- Some showers and thunderstorms are still moving across central
  and southeastern IL early this morning as a cold front pushes
  south. Behind the cold front, a weak high pressure center
  will build over the Midwest later today into tomorrow.

- A persistent northwest flow will keep temperatures and
  humidity levels in check the next several days, with
  seasonable highs in the upper 70s to mid 80s and lows in the
  upper 50s to 60s.

&&

.DISCUSSION...
Issued at 209 AM CDT Thu Aug 20 2026

Earlier in the night, there was some considerable flash flooding
that occurred north of I-72. Some showers and thunderstorms are
still moving across central and southeastern IL this morning but the
flash flooding threat appears to have ended. Heavy rain is still
possible in the stronger showers as this cold front exits off to the
south this morning.

Behind the cold front, a weak high pressure center will build over
the Midwest later today into tomorrow. Today is looking to be quite
pleasant. There could be some sprinkles/light rain in south central
IL this afternoon, but rainfall amounts should be minimal. Friday
there is a 20-40% chance of additional showers, perhaps some thunder
too, area wide as a weak upper disturbance passes overhead.

After Friday, a primarily dry forecast is on deck through early next
week, with temperatures in the upper 70s to 80s for highs and
upper 50s to 60s for lows.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1203 AM CDT Thu Aug 20 2026

Light winds and low dewpoint depressions will lead to patchy
visibility reductions through sunrise, with 3-6SM likely at
times. Otherwise VFR conditions are expected through Thursday
evening along with light northeast winds.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

KEY MESSAGES...Copple
DISCUSSION...Copple
AVIATION...25