Excessive Heat — Southern Harrison County, Mississippi

2025-07-23 · Southern Harrison County, Mississippi

Event narrative

A combination of heat and humidity allowed heat indices to climb into the 113-115 degree range on July 23rd, which meet extreme heat conditions.

Wider weather episode

On July 23, 2025, a dangerous combination of oppressive heat and humidity gripped southeast Louisiana and southern Mississippi, driving heat indices into the 113'115F range. The synoptic setup shown in the surface analysis depicts a weak frontal boundary stalled well to the north, leaving the Gulf Coast entrenched in a hot, moist air mass with southerly surface flow. At 500 mb, broad ridging and subsidence extended over the region, suppressing vertical motion and allowing intense insolation to dominate. This upper-level pattern effectively 'capped in' the heat, preventing relief from convection while enhancing compressional warming. Together, the stagnant surface boundary, Gulf moisture advection, and mid-level ridge created the perfect environment for extreme heat stress, leading to widespread excessive heat conditions across the area.

Source: NOAA Storm Events Database, event_id 1286974. Narrative written by the NWS forecast office that issued the report.