Heat — Zapata, Texas

2023-06-16 · Zapata, Texas

Event narrative

The Zapata County Airport AWOS reported a heat index of 111 by around 3 PM CDT, with 111 or higher values persisting until approximately 8 PM CDT. Peak value was just below 113 at 415 PM CDT. Proxy observations to other sites along the Rio Grande in Zapata County suggest duration could have reached 5 to 7 hours in a few locations during the same time.

Wider weather episode

A dome of strong atmospheric high pressure - known locally as La Canicula, provided a prolonged period of hot to very hot temperatures combined with high humidity to lead to excessively heat index values in mid-June. High temperatures were in the upper 90s to middle 100s June 13th through June 17th. Heat indices ranged from 116 to 125-degrees every afternoon across much of the area, from Hidalgo and Brooks County eastward. Heat indices ranged from 111 to 115 in these counties and farther west (Jim Hogg, Starr, and Zapata) on occasion through the period; these are considered Heat Advisory days with a slightly lower threshold for life-threatening conditions, but still dangerous.

The heat dome would continue through the end of June, with advisory or warning level heat index for all or part of the Rio Grande Valley and Deep South Texas through the period, and into July.

Local hospitals noted an increase in heat-related emergency room visits during this period when compared with the same period a year earlier, which was also hot but not at the level of 2023. Percentage increases ranged from 11 to 18 percent more visits during the month of June. Detailed information on heat-related illnesses (actual numbers of injuries or fatalities) was not known as of the end of August.

Source: NOAA Storm Events Database, event_id 1117056. Narrative written by the NWS forecast office that issued the report.