This report describes the typical weather at the Dillon Airport (Dillon, Montana, United States) weather station over the course of an average August. It is based on the historical records from 1998 to 2012. Earlier records are either unavailable or unreliable.
Dillon, Montana has a humid continental climate with warm summers and no dry season. The area within 25 mi of this station is covered by grasslands (42%), shrublands (25%), forests (24%), and croplands (8%).
The month of August is characterized by falling daily high temperatures, with daily highs decreasing from 83°F to 77°F over the course of the month, exceeding 89°F or dropping below 65°F only one day in ten.
Over the course of August, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 1:24 hours, implying an average day-over-day decrease of 2.7 minutes.
The shortest day of the month is August 31 with 13:17 hours of daylight; the longest day is August 1 with 14:42 hours of daylight.
The earliest sunrise is at 6:15am on August 1; the latest sunset is at 8:57pm on August 1; the latest sunrise is at 6:51am on August 31; the earliest sunset is at 8:08pm on August 31.
Daylight savings time is observed in 2012 but it neither starts nor ends in August, so the entire month is in daylight time.
The median cloud cover is 1% (clear) and does not vary substantially over the course of the month.
On August 16, a representative day, the sky is clear or mostly clear 84% of the time, partly cloudy 4% of the time, and mostly cloudy or overcast 11% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around August 1, occurring in 33% of days. Precipitation is least likely around August 31, occurring in 26% of days.
Throughout August, the most common forms of precipitation are thunderstorms and light rain.
Thunderstorms are the most severe precipitation observed during 62% of those days with precipitation. They are most likely around August 1, when it is observed during 23% of all days.
Light rain is the most severe precipitation observed during 26% of those days with precipitation. It is most likely around August 23, when it is observed during 9% of all days.
Either snow is exceptionally unlikely to fall at this location in August or this station does not reliably report precipitation types.
The relative humidity typically ranges from 22% (dry) to 79% (humid) over the course of a typical August, rarely dropping below 14% (very dry) and reaching as high as 97% (very humid).
The air is driest around August 19, at which time the relative humidity drops below 25% (dry) three days out of four; it is most humid around August 1, rising above 69% (mildly 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 typical August, the dew point typically varies from 31°F (dry) to 52°F (very comfortable) and is rarely below 23°F (dry) or above 57°F (comfortable).
Over the course of August typical wind speeds vary from 0 mph to 16 mph (calm to moderate breeze), rarely exceeding 25 mph (strong breeze).
The highest average wind speed of 8 mph (gentle breeze) occurs around August 31, at which time the average daily maximum wind speed is 16 mph (moderate breeze).
The lowest average wind speed of 7 mph (light breeze) occurs around August 10, at which time the average daily maximum wind speed is 16 mph (moderate breeze).