The heat sweeping through Ohio this week is intense, but it’s not the worst the state has ever seen. Temperatures are expected to climb into the upper 90s°F (32–37°C), with the heat index — factoring in Midwestern humidity — potentially reaching 104°F (40°C) or higher due to a heat dome gripping much of the country. But when exactly was the hottest day ever in Ohio?
The hottest actual temperature ever recorded in Ohio — not accounting for humidity — occurred on July 21, 1934, near Gallipolis, in southern Ohio, when thermometers hit 113°F (45°C). That stands as the state’s all-time high, based on historical weather records.
That sweltering day in July 1934 fell during one of the most infamous heat waves in U.S. history, part of the Dust Bowl era, which scorched much of the Great Plains and the Midwest. With relentless sun and a prolonged drought, Ohio experienced temperatures unlike anything seen before or since.
As for the highest heat index ever recorded anywhere in the world, that title may belong to southern Iran. At Dayrestan International Airport, the heat index reportedly reached 180°F (82°C), with a temperature of 180°F and a dew point of 97°F (36°C), according to data from Global Climate Risks. It’s considered possibly the highest heat index ever documented on Earth.
Here in the United States, while this week’s heat will be dangerously high, unless we surpass the 113°F (45°C) mark, Gallipolis will still hold the record for the hottest temperature ever measured in Ohio.
