Climate Matters: Final heat wave of the month sears off hottest March in U.S. history

The first month of spring ends with another record-breaking heat wave, marking the hottest March in U.S. history. Columbia shattered its record high five times last month and hit a new all-time March high of 93 degrees on March 26th.

Climate change is fueling more of these heat waves, which are hotter, last longer, and extend across more of the year. According to the EPA, data from the 50 largest U.S. metro areas show that heat waves now occur three times more often than they did in the 1960s. Their frequency has increased from about two per year in the 1960s to six per year in recent years.

These cities also see longer and more intense heat waves. Currently, the average lasts about four days, up from roughly three days in the 1960s. Out of the 50 metro areas studied, 46 experienced a significant rise in heat wave frequency, and a similar number saw longer heat wave seasons. Additionally, 28 locations had longer durations, and 20 experienced increased heat intensity.

The intensity of a heat wave is measured by how much temperatures exceed local thresholds. In the 1960s, the average heat wave was 2.0 degrees Fahrenheit above the local 85th percentile threshold, but this has increased to 2.5 degrees in the 2020s.

The typical heat wave season is now 46 days longer than 60 years ago, increasing health risks as early spring and late fall heat waves can catch people off guard.

Austin Krohn, a Public Information Specialist at Columbia/Boone County Public Health and Human Services, advises people to prepare for extreme heat sooner. "Make sure you keep that in the back of your mind when you're out and about and doing things," Krohn says, "The heat will take more of a toll on your body, even though you may not be expecting it this time of year."

With highs in the mid-80s, conditions will feel more like summer, so it's important to start taking precautions now. "The biggest thing is staying hydrated. Then, taking frequent breaks as well, especially if you are one of those individuals that is working outside frequently," Krohn states.

Nighttime lows will also approach record levels in the coming days, which compounds the stress of extreme heat. The body needs time to cool off and rest overnight, and consistently high temperatures make it harder for the heart to cool the body effectively.

"If our nighttime highs are getting exceedingly high, it kind of prevents the body from being able to cool off, and you're kind of under that stress the entire time," Krohn explains. He recommends using cool compresses, taking cool baths, or changing into looser clothing at night to help cool down.

Despite recent increases in frequency and duration, long-term records show that the 1930s experienced the most severe heat waves in U.S. history, mainly during the Dust Bowl in the Great Plains. These extreme events were driven by years of severe drought and poor land practices that depleted soil moisture, reducing the natural cooling effects of evaporation.