The summary climate graph for Harlingen, TX shows a selection of temperature, rainfall and snow minimum, mean and maximum measures over the course of a year. Click on each of the measures in the key to toggle them on and off.
The warmest month in Valley International, Harlingen, Texas is August with an average high temperature of 94.8°F. The hottest day on record was September 4 2011 when the temperature hit 107.1°F. During January the overnight temperature drops to an average of 51.8°F with the lowest temperature of 10.0°F being recorded on February 10 1973.
The warmest days on record are:
| 4 Sep 2011 | 107.1°F |
| 28 Aug 2011 | 106°F |
| 26 Jun 2012 | 106°F |
| 11 May 1974 | 105.1°F |
| 10 Aug 1988 | 105.1°F |
The warmest months on average were:
| August 2011 | 100.5°F |
| August 2012 | 99.1°F |
| August 2009 | 98.7°F |
| July 2009 | 98.7°F |
| July 2012 | 98.7°F |
The coldest days on record are:
| 10 Feb 1973 | 10°F |
| 12 Jan 1962 | 17.1°F |
| 23 Dec 1989 | 17.2°F |
| 25 Dec 1983 | 21.2°F |
| 19 Dec 1996 | 24.8°F |
The coldest months on average were:
| December 1989 | 43.2°F |
| January 1962 | 45.1°F |
| January 1961 | 45.9°F |
| January 1973 | 46.2°F |
| January 1985 | 46.6°F |
The wettest month by average rainfall in Harlingen, TX is September with an average of 1.3 inches of rain falling on 6 to 7 days.Although in January it typically rains on more days with 0.2 inches falling in 7 to 8 days. The driest month by average rainfall in Harlingen, TX is January with an average of 0.2 inches of rain falling on 7 to 8 days. Although in May it typically rains on less days with 0.7 inches falling in 3 to 4 days
The wettest days on record are:
| 28 March 1999 | 2.1 inches |
| 30 March 2006 | 1.7 inches |
| 19 March 1997 | 1.7 inches |
| 13 March 2007 | 1.6 inches |
| 11 March 1986 | 0.8 inches |
The wettest months on record are:
| May 2007 | 11.1 inches |
| September 1998 | 11 inches |
| July 2008 | 10.6 inches |
| October 1997 | 10.3 inches |
| August 2008 | 9.5 inches |
The driest months on record are:
| April 1942 | 0 inches |
| May 1942 | 0 inches |
| June 1942 | 0 inches |
| July 1942 | 0 inches |
| August 1942 | 0 inches |