State Climatologist Justin Glisan says persistent heavy rains that have pummeled parts of northern Iowa in recent weeks can be blamed on a more active weather pattern in addition to an atmospheric condition called the “Ring of Fire.”
“This happens when a low-pressure system is near the state and a high-pressure system is set up over the Mid-Atlantic states. It filters moisture into the central and northern part of the state, so we get wave after wave of precipitation that accumulates day after day,” Glisan said.
Preliminary data shows last month was Iowa’s third-wettest September on record with a statewide average rainfall total of 7.8 inches – about 4.5 inches more than normal. It’s unusual to see the Ring of Fire pattern in the fall, according to Glisan. “Because we have above average precipitation, we typically would expect below average temperatures because of cloud cover, rainfall, and things like that,” Glisan said. “We actually saw above average temperatures connected with above average precipitation. That’s an interesting feature that we typically see in early summer.”
The average temperature in Iowa last month of 66 degrees was about three degrees warmer than normal. September was a record breaker for Waterloo in terms of rain. Waterloo received 13.35 inches of rain, breaking the city’s previous all-time monthly record of 12.82 inches in July of 1999.