Excessive Heat — Howard, Indiana

2023-08-23 to 2023-08-24 · Howard, Indiana

Event narrative

Criteria was reached from maximum heat index values exceeding 110 degrees on the afternoon of August 23rd over essentially all of Howard County. Heat index values were from measured temperature and dewpoint at the OKK AWOS.

Wider weather episode

A very broad and stacked ridge of subtropical high pressure built northward over most of the United States, bringing unseasonable heat and at times record high dewpoints to much of the Midwest. Central Indiana's far western and southwestern counties, as well as central and northern portions of the Indianapolis Metro Area, recorded excessive heat (Heat Index values greater than 110 degrees) on August 20th-21st before a relatively mild day on August 22nd brought only 105-109 degree maximum Heat Index values to the region's southwestern-most zones. August 23rd-25th then saw the region's most pronounced heat and humidity, with Excessive Heat criteria reached on the 23rd over western and northern counties, before the greatest expanse of Excessive Heat on the 24th which enveloped all but far-northeastern zones, with Excessive Heat continuing to persist through the 25th over most central and southern counties.

A cold frontal passage late on the 25th introduced milder conditions, but not before nearly all of the region had recorded at least three consecutive days with Heat Index values surpassing 105 degrees, with many locations observing at least one day with a Heat Index of 115 degrees or greater. Greatest Heat Index values were reported along the lower Wabash Valley, including 122 degrees at Terre Haute on both the 24th and 25th, while a Heat Index of 118 degrees was recorded as far north and east as Kokomo (on the 24th). Indianapolis' heat index officially peaked at 111 degrees on both the 24th and 25th. Highest temperatures occurred on the 25th, including 102 degrees at the Shoals 8 S (Martin County) and 100 degrees at the Farmersburg TV-2 (Sullivan County) COOP sites. Dewpoints amid Excessive Heat were most often in the upper 70s, although a broad swath of low 80s occurred along the entire Wabash Valley on the 23rd, before the Kokomo AWOS reported a dewpoint of 84 degrees on the 24th; Indianapolis' highest dewpoint was meanwhile 81 degrees - reached briefly on both the 24th and 25th.

Daily minimum temperatures trended from the upper 60s to mid-70s on the 21st and 22nd, to several reports of upper 70s on the mornings of the 24th and 25th, including a low of 81 degrees at the Rockville (Parke County) COOP station. Only two of the region's 39 counties (Henry and Randolph) did not reach Excessive Heat criteria, while two others (Brown and Delaware) only verified criteria for a few afternoon hours on a single day (the 24th).

Source: NOAA Storm Events Database, event_id 1138500. Narrative written by the NWS forecast office that issued the report.