INDIANA — The National Weather Service is flagging a moderate to major heat risk across Indiana and surrounding regions on Monday May 18, with temperatures expected to climb into the 80s and 90s alongside high levels of humidity pushing heat indices into the low to mid 90s for portions of the region.
Indiana WX Online confirmed the NWS heat risk designation for Monday May 18, 2026, with portions of Indiana falling under the more serious Major Red Level 3 heat risk category while surrounding states carry the Moderate Orange Level 2 designation.
Major Red Level 3 Heat Risk Covering Portions of Indiana Monday Including Indianapolis
The most serious heat risk on Monday falls across portions of Indiana where the NWS has issued a Major Red Level 3 heat risk designation, indicating dangerous heat conditions that will affect anyone without adequate cooling or hydration as well as placing stress on health systems and industries across the impacted zone.
The Red Level 3 Major category is the second highest on the NWS heat risk scale and signals that Monday’s heat event is serious enough to pose health risks to the general population, not just those who are extremely sensitive to heat.
Indianapolis and surrounding central and southern Indiana communities fall within or near the Major heat risk zone, making Monday a potentially dangerous heat day for a large portion of the state’s population.
Moderate Orange Level 2 Heat Risk Spreads Across Illinois Missouri Kentucky and Ohio
Surrounding Indiana across the broader region, a Moderate Orange Level 2 heat risk is in place covering Illinois including Chicago and St. Louis, Missouri, Kentucky including Louisville, and Ohio including Cincinnati on Monday May 18.
The Moderate Orange Level 2 category indicates heat conditions that will primarily affect those who are sensitive to heat, especially individuals without access to adequate cooling or hydration, as well as placing strain on some health systems and industries across the affected states.
The broad geographic coverage of the orange Moderate zone stretching from Kansas City and St. Louis eastward through Indianapolis, Cincinnati, Louisville, and into Pittsburgh confirms that Monday’s heat event is a widespread and regionally significant weather story.
Heat Indices Reaching Low to Mid 90s as High Humidity Amplifies Monday Heat Danger
Beyond the raw temperature readings in the 80s and 90s, high levels of humidity across Indiana and the surrounding region will drive heat indices into the low to mid 90s for portions of the area on Monday, amplifying the feel of the heat well beyond what thermometers alone will indicate.
Heat index values in the low to mid 90s in combination with the NWS Major heat risk designation make Monday a day where residents across Indiana are strongly urged to stay hydrated, limit outdoor exposure during peak heating hours, and check on vulnerable neighbors, elderly residents, and those without air conditioning.
Forecasters have committed to providing additional updates as Monday approaches and the heat risk picture becomes further refined across Indiana and the broader region. Stay with GordonRamsayClub.com for the latest updates.
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