Iowa wilted under summer’s extreme heat. Meteorologist explains why

The latest heat wave to ripple through Iowa brought the hottest weather of the summer so far.

Feels-like temperatures on Aug. 23 in Eastern Iowa reached 120 degrees. Some in Cedar Rapids battled through the heat without electricity when Alliant Energy suffered an outage that afternoon. Others had toiled through the high temperatures all week without air conditioning, faced with a lack of access to cooling assistance.

It was the latest hot spell in a warm and very dry season for Iowa. Drought conditions have plagued the state since early summer, a mere month after flooding along the Mississippi River. The conditions have thrown Midwestern corn harvests in jeopardy. They also threaten the well-being of farmworkers, tending to the region’s crops without the proper safeguards.

As another round of hot weather sweeps through Iowa this week, The Gazette spoke Monday with meteorologist Matt Friedlein of the National Weather Service Quad Cities Bureau about the summer heat, why it’s happening and what to expect going forward. His answers are edited for brevity and clarity.

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Q: Can you summarize the heat we’ve experienced this summer?

A: There have been three times where we've issued heat headlines for Eastern Iowa, including two excessive heat warnings — one in late July and one in late August.

The most pronounced and dangerous of the three was the most recent one starting on Aug. 20. It was the longest lasting, had the hottest temperatures and the highest feels-like temperatures, or heat indices. That lasted most of the week.

For the summer as a whole, we are above normal for our temperatures, and the multiple heat episodes have a large part in that. There have been less days with rain and thunderstorms than normal, going from late March all the way through now. And when we've had them, they've tended to be severe. Those ups and downs are classic Midwest.

Q: How does heat this summer compare with previous years?

A: Late August’s heat was especially pronounced and somewhat unique in both the lateness and the duration of that heat episode. But comparable to previous summers? It's a little tough to say yet. We usually complete our numbers once we get to the end of August, so data hasn’t been tallied in entirety.

It’s more challenging when you're talking about putting multiple summers together to look for trends. That would require a little more digging. I think the best way of telling it would be number of heat episodes, but that it gets a little challenging and somewhat more subjective to quantify.

I think the most pronounced things this year are the prolonged stretches of dryness we've had, especially at the start of summer in May and June. It's just been almost episodic, I guess, in both heat and thunderstorms. It hasn’t been weeks on end of real wet patterns.

We have seen a trend for more frequent extremes in terms of heat and cold, dry and wet, intense severe weather and then intense dry spells. There's been work to show that, and we've noticed that for some weather variables, but I can't say specifically if that's the case here.

Q: Can we attribute this summer’s extreme heat to climate change?

It’s always challenging to attribute something more on a local scale to larger global climate change.

One thing about the August heat episode was that it was very expansive. NWS heat headlines were in effect for 20 states at one time. That's a lot for heat. Also, some parts of the southern U.S. have had remarkable stretches of heat this summer. So, this has been widespread and unrelentless.

The publications and research out there say more frequent extremes is a probable risk with climate change. From spring into summer, we have seen some extremes locally and regionally: a tornado outbreak on March 31, the dryness of May and June, and a couple of severe weather events including a derecho on June 29. It's always a challenge to directly say whether or not it's climate change. It's possible there could be a correlation there, but unfortunately I'm unable to see that with limited data right now.

What can be challenging for the public to understand is that climate change doesn't always mean hot, especially in the center of a continent we're close to here in Iowa. The roller coaster nature is sharper. There is just bigger gradients and bigger changes happening with temperatures and precipitation.

Q: How has the heat impacted drought conditions in Iowa?

A: Drought conditions are continuing across the state. The most common intensities for most areas are moderate to severe drought. Some are a little less than that. And then a few counties are on the extreme end, but that's spotty right now. The Cedar Rapids area is technically in severe drought.

(Conditions in the Cedar Rapids area have since degraded to extreme drought — the second-highest drought condition — along with most of Linn County and 18 percent of Iowa.)

Obviously, the heat wave in August exacerbated the dry conditions again. A combination of heat and a lack of precipitation over a prolonged period could exacerbate things even more.

Q: What can we expect for the rest of the summer? Any more heat waves to come?

A: Labor Day weekend into the next work week is looking hot. It doesn’t look like we’re under the center of the heat dome this time. However, we may get well into the 90s. If it gets to the upper 90s, we could have pretty high heat indices again. It may not be as humid as earlier this summer, though.

Since we're not under the center of the heat dome, we may have better chances of getting some thunderstorms. They tend to be on the periphery of heatwaves for us. The heat wave in late August was somewhat rare because basically the whole week we didn't have much of a chance of thunderstorms. This week, we'll have at least some small chances daily for thunderstorms.

Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com