September in McAllen averages a daily high of 34.4°C with nights around 23.4°C. Expect roughly 5.7 wet days totalling 96.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit McAllen is November–March.
Based on MCALLEN, TX US (2.4km), 1995–2024. 27 years of September data.