COLUMBUS, Ohio (WCMH) — Last week’s exceptional heat and humidity provided the energy for several rounds of severe storms that toppled trees and brought down power lines, resulting in hundreds of thousands of Ohioans losing power in the midst of historically steamy weather on Tuesday.

The heat index, based on a combination of heat and moisture (dew point) in the air, peaked at 117 degrees at 6:45 p.m. Tuesday at John Glenn Columbus International Airport, exceeding the previous record of 116 degrees on July 15, 1995.

The dew point — a measure of the amount of moisture in the air — briefly climbed to 84 degrees Tuesday evening and easily surpassed the previous record of 81 on July 26, 1997. The National Weather Service in Wilmington noted that in earlier years dew point data was only available hourly, so it’s possible a slighter a higher value than previous maximums could have occurred in between the observation times.

The moisture accumulated, or pooled, in the wake of a barrage of thunderstorm systems Monday night, with two more episdoes during the night, accompanied by winds of 60 to 80 mph in some areas. Fort Wayne recorded a record wind gust of 98 mph, as the storms intensified over northern Indiana, before diving southeast across the Buckeye State between 10 p.m. and 2 a.m.

The NWS office in Cleveland reported three tornadoes touched shortly before midnight in Morrow, Knox, Richland and Ashland counties, including storms that crossed county lines, with wind speeds estimated as high as 105 mph. The thunderstorm system was classified as a derecho, with areas of wind damage from southern Wisconsin and the Chicago area Monday evening (June 13) extending southeastward across central Ohio. The minimum distance required for a derecho is 250 miles of nearly continuous wind damage.

The third in a series of storm complexes, which originated over southwestern Lower Michigan, pounded north-central and eastern sections of Ohio between 2 a.m. and 6 a.m. A derecho is a powerful cluster of storms congealing into a bowing line of severe straight-line winds focused near the apex of the squall line, with an occasional embedded spin-up tornado on the leading edge of rain-cooled air flowing out of the gust front.

More than 106,000 Duke Energy customers in the Cincinnati and Dayton areas lost power in the Monday evening storms that spawned an EF1 tornado in Pike County. AEP Ohio suffered severe outages Monday night, as a second round of storms pounded the northern counties.

As of Tuesday at 8 p.m., the utility provider reported more than 250,000 power outages statewide. The situation was compounded by high demand in sweltering conditions Tuesday afternoon that resulted in power being shut off in parts of central Ohio to prevent more widespread outages due to the heavy load on power lines, according to AEP Ohio.

A storm update posted at 3 p.m. on Thursday by AEP Ohio read: “Lightning and winds in excess of 75 miles per hour brought down more than 350 poles and 2,100 spans of wire across our service territory. In remaining hard-hit areas, drones and helicopters continue to be used to assess damage.”

A cold front crossed the state Friday morning, bringing much cooler temperatures and lower humidity over the weekend. However, a return to hot and humid weather is expected beginning on Tuesday, when afternoon temperatures will be back in the low 90s in central Ohio. The heat index Wednesday could reach 100 degrees, before scattered storms break out ahead of a cold front.