This report describes the typical weather at the Valley International Airport (Harlingen, Texas, United States) weather station over the course of an average year. It is based on the historical records from 1984 to 2012. Earlier records are either unavailable or unreliable.
Harlingen, Texas has a warm humid temperate climate with hot summers and no dry season. The area within 25 mi of this station is covered by grasslands (81%), oceans and seas (7%), croplands (6%), and lakes and rivers (4%).
Over the course of a year, the temperature typically varies from 50Â°F to 96Â°F and is rarely below 38Â°F or above 99Â°F.
The warm season lasts from May 23 to September 19 with an average daily high temperature above 90Â°F. The hottest day of the year is August 7, with an average high of 96Â°F and low of 76Â°F.
The cold season lasts from December 2 to February 18 with an average daily high temperature below 75Â°F. The coldest day of the year is January 4, with an average low of 50Â°F and high of 69Â°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 10:30 hours of daylight; the longest day is June 20 with 13:47 hours of daylight.
The earliest sunrise is at 6:37am on June 13 and the latest sunset is at 8:27pm on July 5. The latest sunrise is at 7:43am on March 11 and the earliest sunset is at 5:38pm on December 1.
Daylight saving time (DST) is observed in this location during 2012, starting in the spring on March 11 and ending in the fall on November 4.
The median cloud cover ranges from 22% (mostly clear) to 75% (partly cloudy). The sky is cloudiest on January 12 and clearest on August 7. The clearer part of the year begins around May 21. The cloudier part of the year begins around November 20.
On August 7, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 66% of the time, and overcast or mostly cloudy 21% of the time.
On January 12, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 55% of the time, and clear or mostly clear 34% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around September 13, occurring in 35% of days. Precipitation is least likely around July 13, occurring in 22% of days.
Over the entire year, the most common forms of precipitation are light rain, thunderstorms, and moderate rain.
Light rain is the most severe precipitation observed during 42% of those days with precipitation. It is most likely around January 13, when it is observed during 18% of all days.
Thunderstorms are the most severe precipitation observed during 25% of those days with precipitation. They are most likely around August 28, when it is observed during 13% of all days.
Moderate rain is the most severe precipitation observed during 16% of those days with precipitation. It is most likely around September 28, when it is observed during 7% of all days.
During the warm season, which lasts from May 23 to September 19, there is a 26% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of thunderstorms (42% of days with precipitation have at worst thunderstorms), light rain (28%), moderate rain (15%), and heavy rain (13%).
During the cold season, which lasts from December 2 to February 18, there is a 32% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light rain (53% of days with precipitation have at worst light rain), drizzle (18%), moderate rain (16%), and thunderstorms (9%).
Either snow is exceptionally unlikely to fall at any time during the year at this location or this station does not reliably report precipitation types.
The relative humidity typically ranges from 45% (comfortable) to 96% (very humid) over the course of the year, rarely dropping below 25% (dry) and reaching as high as 100% (very humid).
The air is driest around August 3, at which time the relative humidity drops below 49% (comfortable) three days out of four; it is most humid around September 12, exceeding 94% (very humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a year, the dew point typically varies from 44Â°F (dry) to 77Â°F (oppressive) and is rarely below 28Â°F (dry) or above 79Â°F (oppressive).
There are two periods in the year that are most comfortable: The first is between January 1 and March 26 and the second is between November 17 and December 31. The air feels neither too dry nor too muggy during these periods.
Over the course of the year typical wind speeds vary from 0 mph to 22 mph (calm to fresh breeze), rarely exceeding 30 mph (strong breeze).
The highest average wind speed of 13 mph (moderate breeze) occurs around April 29, at which time the average daily maximum wind speed is 21 mph (fresh breeze).
The lowest average wind speed of 9 mph (gentle breeze) occurs around September 4, at which time the average daily maximum wind speed is 18 mph (moderate breeze).