The 2025 South Texas International Half Marathon has concluded.

South Texas International Half Marathon

Race complete
Donna, TX, USA · December 7, 2025·
cloudy64°·65° high·Light·Dry
5
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Race Day Weather

cloudy
64°at start
89° high
Breezy
Dry
Your goal
0:00:00

Comfortable temps, big temp swing, moderate wind

Starting at 64°F, heat will be a factor from the gun — go out conservative and stay on top of hydration. Temps will climb significantly to 89°F by later miles, so expect fading conditions as the race progresses. Moderate winds around 12mph may affect pacing on open sections of the course. Moderate humidity at 72% is worth noting for effort level, especially in later miles.

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Pace Calculator

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Race Info

The South Texas International Half Marathon covers 13.1 miles through the Rio Grande Valley of South Texas. The race starts on US Business 83 in Mercedes, just west of the Cameron County line, and is run on the same December morning as the full marathon.

Race weekend

Sunday, December 7
6:30 AMMarathon (26.2 mi)
6:30 AM6-Person Relay (26.2 mi)
7:30 AMHalf Marathon (13.1 mi)
Area Map

Course Map

FAQ

When is the 2025 South Texas International Half Marathon?

The 2025 South Texas International Half Marathon will be held on Sunday December 7, 2025.

What will the weather be like for the 2025 South Texas International Half Marathon?

The forecast calls for a high of 89°F and a low of 64°F with a 0% chance of rain. Check our detailed hourly forecast above for the best half marathon race plan.

Historical Weather

Based on 3 years of data
Avg Temp
58°F
L:57° H:60°
RunScore
7
Conditions
Rain Freq
0%
0 of 3 yrs
Wind3mph
Dew56°F

Temperature History

Range of temperatures during race hours for each year.

Detailed History

YearConditionsLow / HighRainScoreResults
2025
partly-cloudy-night
64°/65°-
5
2024
cloudy
51°/53°-
9
2023
clear-night
56°/61°-
7