Unseasonably warm weather delays frost and extends pest season in Michiana

SOUTH BEND, Ind-- Morning temperatures have brought a hint of fall, but by afternoon, it still feels like summer across Michiana. So far this season, South Bend has yet to experience frosty conditions—and it may be some time before lows drop that far.

Historically, South Bend sees its first frost around Oct. 4. Last year, the first frost didn’t arrive until Oct. 16, when temperatures dipped to 35 degrees. The earliest frost on record occurred on Sept. 10, 1917, while the latest was Nov. 3, 1973.

Although some parts of Michiana have recorded temperatures below 40 degrees this fall, South Bend has remained milder. Forecasts indicate that low temperatures will stay about 10 degrees above average through the middle of next week, when conditions are expected to gradually return to seasonal norms.

The continued warmth is doing more than just delaying frost—it's also extending the active season for insects. Frost plays a crucial role in pushing many bugs into dormancy, but with mild conditions persisting, pests remain active later than usual.

Despite a few brief cool spells, September was largely dominated by warmer-than-normal temperatures. This is concerning, as prolonged warmth keeps “bad bugs” like mosquitoes and ticks active well into the fall. These insects aren’t just a nuisance—they’re known carriers of serious diseases, including West Nile virus, Zika virus, and Lyme disease.