textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 628 AM CDT Mon Aug 31 2026

- Very hot, record to near record-breaking temperatures and rain- free conditions are expected to persist this week.

- Widespread Major (Level 3 of 4) with increasing areas of Extreme (Level 4 of 4) Heat Risk is expected through this week.

- Worsening drought conditions are expected to continue this week due to the combination of very hot temperatures, antecedent dry conditions, and very high evaporation rates.

- The combination of dry fuels, lowering relative humidity values, and hot temperatures will continue to lead to elevated fire danger risks through this week.

- Day-to-day chances for showers and thunderstorms along the sea breeze could emerge next weekend into the following week; currently have low-medium (20-40%) chances next Sunday and Monday (Sept 6-7); best chances along and east of IH-69C/US-281.

DISCUSSION

Issued at 1050 PM CDT Sun Aug 30 2026

Hotter than normal temperatures (in some cases record to near record- breaking), mainly dry, and at times breezy conditions will be the theme through the upcoming workweek. Over the weekend, the persistent, highly advertised, and impactful heat dome shifted eastward from the Desert Southwest Region. It now stretches from the Southern Plains to the Mid South and Ohio Valley Regions. While the relentless heat will continue across the Southern Plains, this heat dome will bring a renewed episode of dangerous heat across the parts of the Midwest including the mid-Mississippi Valley and the Ohio Valley this week.

The core of the heat from this 591-594 dam heat dome will be to our north (from central Texas and points northward). Regardless of its northward position, the combination of mostly sunny skies and a positive feedback loop from the very dry soils will aid in a continuation of very hot temperatures across Deep South Texas and the Rio Grande Valley through this week. Some of these temperatures could be record-breaking (see CLIMATE SECTION).

That said, high temperatures will continue in the low to mid 100s for much of the area including Brownsville and Harlingen through this week. The only area for some relief will be along the coast and over South Padre Island, where highs will range from the mid 90s to mid 80s. Elevated humidity levels will continue to result in peak heat indices ranging between 105-115F degrees each day this week. Special Weather Statements (SPSs) or Heat Advisories may be needed at times through the week for at least parts of the region. Overnight lows will continue very warm as well with overnight low temperatures in the 70s to lower 80s. Given the situation, widespread Major (Level 3 of 4) to increasing areas of Extreme (Level 4 of 4) Heat Risk can be expected through this week.

Temperatures will remain hot over the weekend through early next week. However, there are some indications amongst forecast models that showers and thunderstorm activity along the sea breeze could increase. That said, day-to-day sea breeze showers and thunderstorms are possible next Saturday through the following Monday (Sept 5-7). Currently we have low-medium (20-40%) chances for showers and thunderstorms next Sunday and the following Monday (Sept 6-7). The best chances will be areas closer to the coast (i.e. along and east of IH-69C/US-281).

Borderline elevated fire weather concerns will continue through the week due to the combination of breezy winds, antecedent dry soils, and relative humidity (RH) values getting around Fire Danger Statement (RFD) Criteria.

AVIATION

(12Z TAFS) Issued at 628 AM CDT Mon Aug 31 2026

VFR conditions are forecast to continue through the TAF period. Winds are forecast to increase to around 10 knots out of the southeast late this morning with wind gusts increasing to around 20 knots this afternoon.

MARINE

Issued at 1050 PM CDT Sun Aug 30 2026

Favorable marine conditions are expected to continue through early next week with low seas (1 to 2 foot wave heights) and light to moderate southeasterly winds. Shower and thunderstorm activity is possible beginning next weekend over the Bay and Gulf Waters.

CLIMATE

Issued at 1036 PM CDT Sun Aug 30 2026

A broad and anomalously strong 591-594 dam sub-tropical heat ridge over the Southern Plains to the Ohio Valley will continue to bring hotter than normal temperatures to Deep South Texas and the Rio Grande Valley this week. Mostly sunny skies and a positive feedback loop between the heat and very dry conditions will help to aid in record to near record-breaking temperatures at times this week. Below is a list of the record highs from August 31st to September 4 from our three official climate sites.

Record High Temperatures from August 31st to September 4th:

Monday, August 31, 2026

Brownsville: 103F (2023) Harlingen: 104F (1958) McAllen: 104F (2023, 2017)

Tuesday, September 1, 2026

Brownsville: 100F (2023, 2020) Harlingen: 103F (1928, 1952) McAllen: 106F (2018)

Wednesday, September 2, 2026

Brownsville: 99F (2018) Harlingen: 104F (1928, 1937) McAllen: 106F (2018)

Thursday, September 3, 2026

Brownsville: 102F (2011) Harlingen: 106F (2011) McAllen: 106F (2011)

Friday, September 4, 2026

Brownsville: 103F (2011, 2000) Harlingen: 107F (2011) McAllen: 108F (2011)

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 98 80 98 80 / 0 0 0 0 HARLINGEN 102 76 102 76 / 0 0 0 0 MCALLEN 104 80 104 81 / 0 0 0 0 RIO GRANDE CITY 105 78 105 79 / 0 0 0 0 SOUTH PADRE ISLAND 90 81 90 81 / 0 0 0 0 BAYVIEW/PORT ISABEL 96 78 96 79 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

TX...None. GM...None.