Iowa set a record for rain and snow over the past 12 months, according to data from the National Oceanic and Atmospheric Administration.

A changing climate and above-normal ocean temperatures thousands of miles away contributed to the state's 50.73 inches of precipitation from June 2018 through May 2019, state weather experts say.

That's about 16 inches more than the 34.42 inches the state averaged per year from 1981 to 2010.

“If you look at the short term, the past 12 months have been the wettest (since official records began in) 1895,” said Justin Glisan, the state climatologist. “With drought conditions in southern Iowa last year, that’s a pretty remarkable flip.”

And it's not done yet.

Iowa can expect more precipitation as temperatures increase, Glisan said. Higher temperatures create more water vapor in the atmosphere that leads to more rain, he said.

The USDA Midwest Climate Hub in Ames is predicting higher than average rainfall for most of the summer.

While there is no one cause behind Iowa's record rainfall, state weather officials point to climate change and El Nino conditions over the Pacific Ocean as contributing factors.

“Right now, we’re trying to figure out what started the fire while the fire is still burning,” said Andrew VanLoocke, an assistant agronomy professor from Iowa State.

El Niño conditions, characterized by above normal ocean temperatures in the eastern and central portions of the Pacific Ocean, can affect weather patterns across North America. For Iowa, that means higher than normal temperatures and rainfall.

It is one of the most important factors that influence crop weather in the Midwest, according to the ISU Department of Agronomy.

El Niño aside, USDA Midwest Climate Hub Director Dennis Todey said the increased precipitation is part of the state's overall changing climate.

“The projections are that more and bigger rainfalls are going to continue on a seasonal basis, especially in the spring," he said. "These big rainfall events in the spring produce bigger flooding issues because when that rain falls on top of snow, you get the snowmelt that we saw in parts of Iowa and Nebraska.”

Iowa and Nebraska both experienced heavy flooding in March after heavy rains and snowmelt overflowed the Missouri River, destroying levees, inundating cities and farmland with water, and closing Interstate Highway 29 between Omaha and Kansas City.

Iowa officials say damages have totaled more than $2 billion, a state record.

President Donald Trump approved a major disaster declaration for 56 of Iowa's 99 counties in March, making them eligible for federal assistance. Individual assistance was granted for residents living in five counties along the Missouri River.

Iowa's precipitation levels in April were slightly below average, but in May, the rainfall in southern and eastern Iowa was 150 to 200 percent above average, which resulted in devastating flooding in Davenport and Burlington, Glisan said.

'We will see more extremes'

Iowa’s record February snowfall of 22.6 inches was a big contributor to Iowa’s wettest year, according to the state climatologist.

Iowa’s average snowfall for February is around 6.5 inches.

Glisan said Iowa is seeing more precipitation in the spring, but it’s coming earlier, while snow is still on the ground.

“That snowmelt brought record runoff after the heavy rains fell on top of existing packed snow,” Glisan said.

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Extreme weather and increased precipitation are becoming more common and will continue, Todey said.

“Much of the middle part of the U.S. is getting wetter over time,” he said. “This is not a surprise. The extreme (nature) of it is something big to talk about.”

While individual rainfalls have become slightly larger due to climate change, VanLoocke said, Iowa has also experienced more consistent rainfall.

“People will point to when it rains, it rains heavier. But actually, it’s smaller rain and a lot of it,” he said.

“Things don’t happen in isolation in weather and climate,” VanLoocke said. “As climate change continues to alter our patterns, we will see more extremes. When we get heavy rains, they will be heavier because a warmer atmosphere can hold more water.”

'They're starting to bite now'

The heavy rains have left standing water throughout the state that will result in larger mosquito populations once summer humidity hits, Glisan said.

“We’ve had a delay in mosquito emergence because of the coolness in the springtime,” he said. “They’re starting to bite now.”

AccuWeather, which produces a forecast specifically focused on the pest, predicts high mosquito activity in Des Moines for much of the next two weeks.

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“Mosquitoes have increased due to this wet weather. We can say that with certainty,” VanLoocke said. “This weather will affect the insect population for sure.”

The rain has also caused headaches for Iowa farmers, delaying planting.

About 80 percent of Iowa’s corn acres had been planted as of June 3, compared to 99 percent in a normal year, according to USDA data.

Earlier this month, the U.S. Department of Agriculture lowered its estimate for this year's corn crop by 1.4 billion bushels to 13.7 billion bushels, the lowest since 2015.

The delay in planting comes as Iowa farmers are already struggling with low commodity prices and increased pressure from ongoing trade disputes with China, Mexico and Canada.

U.S. farm income this year is projected to be $69.4 billion, about 45% below a 2013 high.

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“This is a struggle for the farmers,” VanLoocke said. “They’re trying to run operations of planting across a big radius. When you have weeks with less than two workable days, it means that the whole logistics break down.”

VanLoocke added that the struggle isn’t over when the seeds are planted. The climate has been delaying other aspects of the farming schedule as well.

“For those farmers that got their field planted, it’s not over yet. They had to wait until very recently to do fertilizer application due to weather. The emergence is way behind schedule,” he said.

Only 51 percent of Iowa’s corn has achieved emergence, compared to 91 percent on average by June 10 during a normal year, according to Iowa State University.

Agriculture and related industries contribute $112.2 billion a year to Iowa’s economy and provide 20 percent of jobs in the state, according to the Iowa Farm Bureau. VanLoocke said when these services are impacted by weather, it can leave Iowa vulnerable.

“We need revenue from farming to run our state,” he said. “It makes us pretty exposed when things don’t go so well.”

Editor's note: This story has been updated. The past 12 months have been Iowa's wettest since records began in 1895.

Gage Miskimen is the growing suburbs reporter for the Register. You can reach him by email at gmiskimen@dmreg.com or by phone at 515-284-8234.