Historical weather data, all-time temperature records, and monthly climate averages for Harlingen, TX. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th in Harlingen typically feels like summer already — the average high hits 85° with almost no chance of rain at just 13%. The date has seen wild swings in 107 years of records, from a scorching 101° in 1955 down to a jarring 39° low back in 1920.
Harlingen plays for keeps: the all-time high of 108° in August 1915 and a record low of 14° in January 1962 show just how wide this South Texas city's weather range can stretch. Even snow isn't unheard of — Christmas Day 2004 brought 1.5 inches, and last year a single storm dumped 10 inches of rain on March 28, 2025.
Harlingen runs hot most of the year, with highs in the 90s from May through September and a peak average of 97° during the last week of July. Even "winter" is mild — the coolest stretch of the year, January 8–14, averages a high of 69°. If you're watching for rain, aim for late September, the wettest week of the year at 1.37 inches on average.