East St. Louis, IL 62205 Weather

Key messages

- Warmth persists through Friday with temperatures well into the 70s to near 80 degrees over much of the area.

- Variable precipitation chances extend from late Thursday through the weekend, but there will be plenty of dry time between showers. Better chances of rain arrive early next week.

Short term

Issued at 222 PM CDT Wed Oct 28 2026

High pressure encompasses the eastern U.S. coastline and extends westward through the southern half of the Mississippi Valley this afternoon. Mid to high clouds, originally accompanied by a few light showers over central Missouri this morning, have all but dissipated as they approach the Mississippi River this afternoon. Mostly sunny skies have dominated much of the region with light southerly flow and temperatures rising through the 70s. Highs are expected to top out in the upper 70s to near 80 degrees.

A weak cold front, which trails southwest of a Canadian low pressure system, will slowly sag southward into northern Missouri tonight into Thursday. Tonight's lows are dependent on increasing cloud cover, mainly impacting the northern sections of the CWA. HREF data shows the best probability (30-60%) for scattered/broken ceilings extending from Moberly, MO to Quincy, IL and northward with dry air winning out to the south. This will keep Thursday morning lows a little milder (mid/upper 50s) and cooler air to the south (upper 40s/ mid-50s).

The main items to focus through Thursday are the stalling cold front, increasing clouds, and late evening rain showers. RAP guidance shows dewpoints near 60 degrees pooling along the front from Kansas City, MO through Quincy, IL. Higher RH is gradually pull northeastward around the eastern ridge with HREF indicating clouds may increase quick enough to impact high temperatures along and west of the Mississippi River. NBM has been bullish with highs in the low- 80s and while this may be plausible with clear skies, moisture trends and HREF temperature data would counter this with upper 70s. Highs were reduced by just a couple of degrees to account for these trends. Precipitation chances are limited (<20%) to the frontal boundary until Thursday in the late evening. The stalled from drifts as far south as the I-70 corridor, but then lifts northward under the western influence of the mid-level ridge. Fragments of mid/upper vorticity lift over the front and induce scattered showers late Thursday night. While NBM probabilities 60-65%, saturation is limited to around 850-900MB, indicating a high prob/low QPF potential heading into early Friday morning with just a few hundredths of rainfall over northeast Missouri and west-central Illinois.

Long term

Issued at 222 PM CDT Wed Oct 28 2026

Temperatures remain quite warm at the start of the period, then trend cooler beyond Friday. Despite rain chances being dispersed through each day of the period, there will be plenty of dry time between showers over the upcoming weekend.

Surface high pressure builds southeastward from southern Canada into the Great Lakes Region through the day Friday. A mid-level ridge compliments the surface feature with easterly surface flow undercutting westerly flow aloft. High clouds will be on the increase as southwest/westerly flow aloft draw moisture in around the western side of the mid-level ridge. Though a stray shower cannot be entirely ruled out north of I-70 Friday, limited support and drier air below 850MB should stave off measurable precipitation.

A shortwave that resides at the base of the western trough tracks northeastward into the central CONUS Saturday. Ascent is broadly spread from the Dakotas southeastward through the Lower Mississippi Valley, which encounter east/southeastly flow as a consequence of the southeastern shift in the Great Lakes surface ridge. This will initially impede moisture from reaching the surface until late Saturday. At that time, dry air below 700MB begins to give way to increasing moisture as the surface high moves over the New England Region. The system is not well organized and produces broadly scattered showers late in the evening into Saturday night with LREF 75th percentile data ranging from 0.15-0.25" from north to south. The lower end of the IQR zeroes out and probabilities for measurable rainfall center on the 6pm-6am period Saturday night into Sunday morning and peak at 30-50%. This suggests that while the area will see rainfall to some degree, it will largely be light.

Attention turns to two upper level waves within the amplified western trough. Long range, global guidance diverges between a cutoff, slow-moving closed low (GFS) and a more progressive amplified trough (ECM) heading into next week. While this brings the best potential for widespread rainfall, the evolution deserves attention to provide better confidence in rainfall amounts. The split flow pattern can often provide early signals for precipitation that, at times, become less promising as the days progress. What is more certain is the lean toward cool temperatures, though they remain seasonably mild. Highs through the period are generally in the low to mid-70s with lows in the 50s.

Aviation

Issued at 611 PM CDT Wed Oct 28 2026

The main aviation concern over the next 30 hours will be wind, as they gradually veer before a weak cold front moves through the area tomorrow afternoon. A few showers cannot be ruled out along the front, but confidence in them occurring is too low to warrant a mention in the TAFs. Additional, broken to overcast skies along the front will lower as they move into the area, perhaps approaching 3,000 ft.

Watches, warnings and advisories

MO: None. IL: None.