| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 21.5° | 9.9° | 26.8mm | 7.1 | 86 |
| February | 23.8° | 12° | 28.4mm | 5.3 | 89 |
| March | 26.5° | 15.1° | 37.9mm | 5.6 | 89 |
| April | 29.7° | 18.6° | 39.8mm | 4.9 | 79 |
| May | 32.4° | 22.1° | 58.3mm | 4.7 | 69 |
| June | 34.7° | 24° | 48.1mm | 5.6 | 58 |
| July | 35.3° | 24.6° | 74.1mm | 5.7 | 55 |
| August | 36° | 24.6° | 51.6mm | 6.2 | 52 |
| September | 33.6° | 22.9° | 117.9mm | 9.7 | 54 |
| October | 30.6° | 19° | 89.5mm | 6.3 | 73 |
| November | 26.1° | 14.7° | 53.6mm | 6.3 | 87 |
| December | 22.6° | 11.2° | 39.4mm | 6.3 | 87 |
January in Harlingen averages a daily high of 21.5°C with nights around 9.9°C. Expect roughly 7.1 wet days totalling 26.8mm. Comfortable conditions for being outdoors all day.
February in Harlingen averages a daily high of 23.8°C with nights around 12°C. Expect roughly 5.3 wet days totalling 28.4mm. Comfortable conditions for being outdoors all day.
March in Harlingen averages a daily high of 26.5°C with nights around 15.1°C. Expect roughly 5.6 wet days totalling 37.9mm. Comfortable conditions for being outdoors all day.
April in Harlingen averages a daily high of 29.7°C with nights around 18.6°C. Expect roughly 4.9 wet days totalling 39.8mm. Comfortable conditions for being outdoors all day.
May in Harlingen averages a daily high of 32.4°C with nights around 22.1°C. Expect roughly 4.7 wet days totalling 58.3mm. Generally workable, with some weather to plan around.
June in Harlingen averages a daily high of 34.7°C with nights around 24°C. Expect roughly 5.6 wet days totalling 48.1mm. Generally workable, with some weather to plan around.
July in Harlingen averages a daily high of 35.3°C with nights around 24.6°C. Expect roughly 5.7 wet days totalling 74.1mm. Generally workable, with some weather to plan around.
August in Harlingen averages a daily high of 36°C with nights around 24.6°C. Expect roughly 6.2 wet days totalling 51.6mm. Demanding conditions — pack for it and plan indoor options.
September in Harlingen averages a daily high of 33.6°C with nights around 22.9°C. Expect roughly 9.7 wet days totalling 117.9mm. Demanding conditions — pack for it and plan indoor options.
October in Harlingen averages a daily high of 30.6°C with nights around 19°C. Expect roughly 6.3 wet days totalling 89.5mm. Generally workable, with some weather to plan around.
November in Harlingen averages a daily high of 26.1°C with nights around 14.7°C. Expect roughly 6.3 wet days totalling 53.6mm. Comfortable conditions for being outdoors all day.
December in Harlingen averages a daily high of 22.6°C with nights around 11.2°C. Expect roughly 6.3 wet days totalling 39.4mm. Comfortable conditions for being outdoors all day.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Harlingen peaks at 89.
Based on 30 years of records, November–March scores highest for comfort in Harlingen, balancing daytime temperature against rainfall.
August is the warmest, averaging a daily high of 36°C.
September is the wettest, averaging 117.9mm of rain across roughly 9.7 wet days.
January is the coolest month, with average daily highs around 21.5°C.