16/07/2025
First Warn 10-Day Forecast | Wednesday, July 16, 2025
St. Louis Metro | Central Missouri | Southeast Missouri | Southern Illinois
Headlines:
Dangerous heat today with heat index values of 100 to 105
Thunderstorms arrive tonight from the north; isolated severe threat
A stalled front keeps storms around Thursday and Friday
Prolonged stretch of heat and humidity likely this weekend into next week
Today brings the hottest weather we’ve seen in some time. Temperatures will climb into the low to mid 90s across the region, with dewpoints in the 70s combining to produce heat index values between 100 and 105. While the heat advisory criteria may not be met for long enough duration today to trigger widespread warnings, this level of heat is still hazardous—especially for those working or spending time outdoors.
With a more dominant ridge in place overhead, we won’t see much in the way of pop-up storms during the day. However, all eyes turn northward tonight. A cold front sliding south through Iowa and northern Missouri will help trigger thunderstorms that may dip into parts of our area after sunset. The greatest severe threat appears to be north of I-70 between 8 p.m. and midnight, with damaging wind gusts as the main concern. The storms are expected to weaken as they push south, but a few could still pack heavy rain and gusty winds, especially where local outflow boundaries intersect. Flash flooding is a secondary concern given the tropical moisture still in place, but the short duration of these storms may limit the widespread flood risk.
On Thursday, that front stalls out somewhere across Missouri and Illinois, and its exact position will determine who stays hot and who gets relief. North of the front, temperatures may only reach the lower 80s, but south of the boundary—particularly in southeast Missouri and the lower Ohio Valley—the mid 90s will persist. The front will also act as a focus for renewed showers and thunderstorms during the afternoon and evening. The severe weather risk appears low due to weak wind shear, but the atmosphere remains unstable and moisture-rich, so localized flooding and brief strong downbursts can’t be ruled out.
Friday looks to be a repeat performance with the stalled front gradually weakening but still hanging around long enough to trigger additional scattered storms, especially in the afternoon. Storms may not be quite as widespread, but any that do develop will carry the same threats: heavy rain, gusty winds, and lightning.
This weekend, the ridge builds back in with authority. Temperatures will climb back into the mid 90s, and with high humidity in place, we expect heat index values of 103 to 107 degrees across much of the region Saturday through at least Tuesday. Some northern portions of Missouri and Illinois could see periodic clouds or storms that hold temps back slightly, but for most of us, this will be the start of a prolonged hot and humid stretch. Heat Advisories—and potentially even Extreme Heat Warnings—may be needed early next week if the current trends hold.
The unsettled pattern doesn’t entirely go away though. While the ridge brings heat, it also allows for occasional shortwaves to ride along the northern edge of the dome. That means we may still see isolated to scattered storms at times, especially north of I-70. However, the bigger concern heading into next week will be the heat and its duration, as the ridge shows signs of holding firm for several days.
Stay hydrated, avoid prolonged outdoor activity during peak heat hours, and keep an eye to the sky later today and again tomorrow—this is shaping up to be a classic stretch of midsummer heat with stormy punctuation marks.
