This report describes the typical weather at the Riverton Regional Airport (Riverton, Wyoming, United States) weather station over the course of an average year. It is based on the historical records from 1986 to 2012. Earlier records are either unavailable or unreliable.
Riverton, Wyoming has a cold semi-arid steppe climate. The area within 25 mi of this station is covered by shrublands (71%), forests (13%), grasslands (11%), and croplands (3%).
Over the course of a year, the temperature typically varies from 9Â°F to 87Â°F and is rarely below -4Â°F or above 95Â°F.
The warm season lasts from June 10 to September 10 with an average daily high temperature above 75Â°F. The hottest day of the year is July 23, with an average high of 87Â°F and low of 59Â°F.
The cold season lasts from November 22 to February 26 with an average daily high temperature below 39Â°F. The coldest day of the year is December 28, with an average low of 9Â°F and high of 27Â°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 9:00 hours of daylight; the longest day is June 20 with 15:23 hours of daylight.
The earliest sunrise is at 5:33am on June 16 and the latest sunset is at 8:58pm on June 25. The latest sunrise is at 7:52am on November 3 and the earliest sunset is at 4:38pm on December 10.
Daylight savings 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 1% (clear) to 24% (mostly clear). The sky is cloudiest on April 12 and clearest on July 24. The clearer part of the year begins around June 1. The cloudier part of the year begins around March 9.
On July 24, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 67% of the time, and overcast or mostly cloudy 13% of the time.
On April 12, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 34% of the time, and clear or mostly clear 50% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around May 17, occurring in 35% of days. Precipitation is least likely around January 2, occurring in 20% of days.
Over the entire year, the most common forms of precipitation are light snow, light rain, and thunderstorms.
Light snow is the most severe precipitation observed during 41% of those days with precipitation. It is most likely around February 10, when it is observed during 21% of all days.
Light rain is the most severe precipitation observed during 32% of those days with precipitation. It is most likely around May 23, when it is observed during 17% of all days.
Thunderstorms are the most severe precipitation observed during 12% of those days with precipitation. They are most likely around July 26, when it is observed during 9% of all days.
During the warm season, which lasts from June 10 to September 10, 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 light rain (56% of days with precipitation have at worst light rain), thunderstorms (29%), and moderate rain (9%).
During the cold season, which lasts from November 22 to February 26, there is a 22% 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 snow (83% of days with precipitation have at worst light snow) and moderate snow (12%).
The likelihood of snow falling is highest around March 4, occurring in 24% of days. The season in which it is relatively likely for snow to fall spans from October 2 to May 19.
Either snow rarely accumulates at this location or snow depth measurements are unavailable or unreliable.
The relative humidity typically ranges from 19% (dry) to 85% (very humid) over the course of the year, rarely dropping below 10% (very dry) and reaching as high as 99% (very humid).
The air is driest around July 9, at which time the relative humidity drops below 23% (dry) three days out of four; it is most humid around December 25, exceeding 80% (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 3Â°F (dry) to 50Â°F (very comfortable) and is rarely below -10Â°F (dry) or above 58Â°F (comfortable).
Over the course of the year typical wind speeds vary from 0 mph to 20 mph (calm to fresh breeze), rarely exceeding 31 mph (strong breeze).
The highest average wind speed of 10 mph (gentle breeze) occurs around April 5, at which time the average daily maximum wind speed is 20 mph (fresh breeze).
The lowest average wind speed of 6 mph (light breeze) occurs around December 26, at which time the average daily maximum wind speed is 12 mph (gentle breeze).