St. Louis is waking up in the low 70s on Monday morning, June 29, 2026, with clear skies and a not-so-subtle warning: this is the cool part. A strong ridge of high pressure is parking over the region and cranking up the thermostat, pushing afternoon highs into the mid to upper 90s and keeping nights uncomfortably warm straight through the July 4 holiday weekend. Factor in the humidity and it will feel downright dangerous, with heat-index readings likely topping 110°F at times.
Extreme Heat Warning Through Friday
The National Weather Service office covering St. Louis has issued an Extreme Heat Warning for the metro area and nearby counties through Friday, July 3, 2026. Forecasters say heat-index values could climb to around 110 to 112°F, a level where heat-related illnesses move from possible to likely if people are not careful, according to the NWS St. Louis.
Afternoon Peak, Little Nighttime Relief
On Monday, expect highs near 97°F, with south winds running about 6 to 12 mph and occasional gusts in the 20 to 21 mph range. That breeze will not offer much relief and will make midday outdoor work or exercise especially risky. From Tuesday through Thursday, the story barely changes - highs hover around 98°F while overnight lows linger in the upper 70s, so the heat follows you into the evening instead of easing off. Forecasters say a few isolated afternoon storms could pop up later in the week, but any downpours are expected to be scattered and unlikely to cool the entire city.
Where To Cool Off And Safety Tips
For residents without reliable air conditioning, the city keeps a list of neighborhood cooling centers and assistance programs. Lean on the basics: drink plenty of water all day, avoid strenuous activity between roughly 11 a.m. and 6 p.m., and never leave children or pets in a parked car, even for a short errand. If someone starts showing signs of heat stroke such as confusion, fainting, or a body temperature above 103°F, call 911 right away. Cooling center locations and hours are listed by the City of St. Louis.
Late-Week Outlook
By the weekend, that stubborn ridge of high pressure may finally begin to loosen up, with rain and storm chances ticking up Friday into Saturday. Any storms that do develop could bring short-lived, localized relief but will not undo the effects of several days of extreme heat. For now, keep holiday plans flexible, stay close to shade and air conditioning when you can, keep the water bottle handy, and check updated local forecasts as St. Louis sweats its way into July.
