Missouri news

It's official: St. Louis had the longest 90-degree season on record

St. Louis Public Radio | By Kate Grumke

Published October 2, 2026 at 8:12 AM CDT

Kenny Marks, owner of Kenny's Upstairs, puts out dozens of bottles of cold bottled water as temperatures climb outside his bar on South Grand Avenue on Sept. 16 in St. Louis' Tower Grove South neighborhood.

The region has seen the longest period between 90-degree days, with the first one in March and the most recent one at the end of September.

If you feel like summer has been extraordinarily long this year, you're right.

This week, St. Louis broke a record for having the longest stretch between 90-degree days in a year.

The first 90-degree day was March 22, while the last was Wednesday. That's 191 days, breaking a record set in 1950.

September was also the warmest on record at 78.4 degrees on average, beating the previous record from 2019, said Jayson Gosselin, a meteorologist with the National Weather Service in St. Louis.

"We didn't have a single day with a below-normal average temperature until the 22nd of the month," Gosselin said.

The influence of climate change was detectable in St. Louis' temperature for 14 days last month, according to Climate Central's Climate Shift Index.

Many individual days also broke records in September, Gosselin said.

"We set three record highs in the month and six record warmest low temperatures, so we had not only daily records, but quite a few of them," Gosselin said. "And again [we had] persistent warmth through the first two-thirds of the month."

Gosselin said the heat advisory that ended on Sept. 19 was the latest the National Weather Service had issued that type of advisory in more than 20 years.