A spokesman for Twin Cities in Motion says they held out hope as long as they could before deciding whether to call off the Twin Cities Marathon.
"We were trying to give every chance we could to being able to say yes to the race," Charlie Mahler told Channel 5's Tom Hauser on the WCCO Morning News on Monday.
Twin Cities in Motion is a non-profit that operates major races in the metro area.
The Twin Cities Marathon has one of the largest numbers of participants of any race in the US.
Coupled with the companion 10-mile race, more than 20,000 runners were registered for Sunday's events.
Mahler said race officials were well aware of the forecast for high heat and humidity, and were monitoring during the days leading up to the race.
They were using the guidelines of the Event Alert System, which has a color-coded system to determine race course conditions.
It goes from green (low) to yellow (moderate) to red (high) to black (event cancelled).
"We were right on the cusp, it's still red, it's still red, but it's really close to black."
It was Sunday morning when the latest forecast showed temperatures reaching into the 90's.
That's when the plug was pulled.
"We realized, it's 5:30, buses are already rolling, people are already making their way to the start line," Mahler said. "We knew that was pretty much our last, best chance to make the decision. That's why we made it when we did."
There were some runners who showed up at the starting line and ran anyway.
They did so without water stops, or medical teams staffing the entire course.
"When you're in the position of race organizer, you take the responsibility of the 20,000 people who are, in a sense, in your hands," Mahler said. "That if things go haywire, people are just going to look back at us and say, gee, why didn't you do something it."
Race organizers will have an announcement about possible refunds for the runners by Thursday night at the latest.