Changes in climate lead organizers of the Twin Cities Marathon to push event back to mid-October

The decision stems from increasingly warmer temps in early October, including 2023's cancellation when the high was 92.

Running a marathon in weather over 90 is highly dangerous and requires significant pacing adjustments to avoid heat exhaustion. Most marathoners prefer conditions much cooler, closer to 50 degrees.

State Climatologist Pete Boulay says it makes sense the event was moved to later in the month simply based on averages. While it can certainly be ideal for a marathon on October 1, there's a higher probability of cooler weather by mid-October.

"Comparing October 1st to October 17th, the normal high and low on the 1st is 66 and the normal low is 47," says Boulay. "Looking at the 17th, normal high is 58 and 40."

Race Director Ed Whetham says it was both a difficult, and easy, decision.

"It was a tough decision in that there's a 45 year history of being mostly the first Sunday of October, so you're battling tradition," he says. "But also easy once you really look at the data."

Boulay says that it is true more recent weather trends show warmer temps lasting into October.

"We're kind of getting an extension of summer," he says. "We've noticed over the years that summer's kind of extended into September, and even early October. And we're seeing that the other things later. A peak of fall colors, it's happening later. "So we've kind of shifted everything and probably more pertinent to the marathon is now we have more record 90s popping up in early October, including back in 2023 where we had a record high of 92."

Boulay adds that since the year 2000, the chances of hot weather in early October have gone way up. But, there's still a quick drop off in the chances of 90-plus degree weather after that first week.

"Just looking at the first week of October compared to the second week of October, it's about 3.3 degrees cooler overall and really, looking at the record highs for the first half of October, seven out of the 15 happened since the year 2000. So, not every year is really hot, but we've had enough of them where unusually warm temperatures for the first week or so of October."

Boulay also says the record high for date they are looking at for the marathon starting next year is only 84.

"It's the percentages game," adds Whetham. "So we're looking at all the data from past years, and especially over the last 10 to 15. The October 11th to the 20th time frame is 98% chance of ideal marathoning conditions, whereas October 1st to the 10th is about 85%."