St. Louis is starting Friday on a gray and relatively cool note, sitting around 66°F in the mid-morning hours of June 5, 2026. Clouds will not stick around all day, though. Sunshine is expected to break through, and temperatures will climb fast, with afternoon highs headed for the upper 80s to around 90°F. South winds will strengthen later, which will make it feel both warmer and a bit on the breezy side.
Afternoon Heat and a Punchy South Breeze
According to the National Weather Service, Friday’s high should land near 90°F, with south winds of 7 to 13 mph and gusts up to 21 mph. Friday night will stay warm and muggy, with lows near 72°F.
Saturday cranks things up another notch. A high near 92°F is in the cards, and dew points are likely to rise above 69°F. That level of humidity could push heat index values into the low to mid 90s. In other words, it will feel firmly like summer by Saturday afternoon, even for St. Louis standards.
Storm Chances Sunday Through Tuesday
Showers and thunderstorms are likely to move in to start Sunday. Storms are expected after 7 a.m. on Sunday, June 7, 2026, with about a 60 percent chance of rain during the day and even higher chances Sunday night.
The unsettled pattern hangs on into Monday, June 8, and Tuesday, June 9. Daily rain chances climb into the 60 to 80 percent range, and many of the storms could bring brief heavy downpours and lightning. Forecasters expect most of the activity to be disorganized, but any stronger cells could produce gusty winds and short-lived, localized downpours that may cut into outdoor plans.
What This Means for Outdoor Plans
Plan to beat the heat on Saturday and dodge the storms starting Sunday. If you have outdoor events, try to schedule them earlier in the day and have a backup shelter plan in case lightning shows up. Staying hydrated, taking breaks in shaded or air-conditioned spots, and keeping an eye on short-term radar are all smart moves, especially if you have evening plans.
If you or someone you know needs help finding a cool place, the City of St. Louis Department of Health lists local heat resources and cooling-site information, and recommends calling 2-1-1 for assistance.
Looking a bit farther down the road, midweek is expected to turn hotter. Highs are forecast to climb into the mid 90s by Wednesday, June 10, and possibly into the upper 90s by Thursday, June 11. The exact timing and coverage of storms may still shift, so it is a good idea to check updated forecasts and radar before heading out over the next several days.
