Heat — Willacy, Texas

2023-10-04 · Willacy, Texas

Event narrative

The Automated Surface Observing System (ASOS) at Brownsville and Harlingen generally reported 2 to 2.5 hours of heat index of 111 or higher, peaking just below 113 degrees just before 3 PM Central Daylight Time. By proxy, and based on maximum temperatures of 99 degrees at Raymondville (maximum at Harlingen and Brownsville were 97 degrees each), it can be assumed that similar apparent temperatures occurred in Willacy County around the same time.

Wider weather episode

The persistent high pressure ridge known locally as La Canicula prevailed through the first five days of October 2023, with the center of the ridge finally shifting to the Lower Texas coast by October 4th, just ahead of the season's first notable cold front which arrived later on the 5th. The combination of southerly flow in an already hot airmass with monthly area-wide afternoon temperatures in the upper 90s to around 100 allowed heat index to reach advisory conditions (111 or higher) for a few hours across the lower Valley.

Source: NOAA Storm Events Database, event_id 1145258. Narrative written by the NWS forecast office that issued the report.