Average Weather at Rio Grande Valley International Airport

Aggregator page built on NOAA data (continuously updated, not a fixed-date publication).

Key findings

Average highs 71°F (Jan) to 95°F (Aug); lows 52–76°F. Rarely below 38°F or above 99°F. “Muggy or worse” days: 30.8/month in July vs. 4.0/month in January — a >7x seasonal humidity swing. Clearest month is May (71% clear/mostly-clear/partly-cloudy days); cloudiest is August (57% overcast/mostly-cloudy) — even the best month falls well short of desert-grade sky clarity. Wet season runs late May–October, with >22% daily precipitation probability across most of the warm season.

Why it matters for this archive

Quantifies exactly how far South Texas is from the clear, dry New Mexico skies the archive’s radiative-cooling physics assumes — cloud cover is elevated across nearly the entire warm season, not just occasionally. See Night-sky radiative cooling § Climate dependency.