This report describes the typical weather at the Missoula International Airport (Missoula, Montana, United States) weather station over the course of an average April. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Missoula, Montana has a humid continental climate with warm summers and no dry season. The area within 25 mi of this station is covered by forests (80%) and grasslands (20%).
The month of April is characterized by rising daily high temperatures, with daily highs increasing from 52°F to 60°F over the course of the month, exceeding 75°F or dropping below 42°F only one day in ten.
Over the course of April, the length of the day is rapidly increasing. From the start to the end of the month, the length of the day increases by 1:33 hours, implying an average day-over-day increase of 3.1 minutes.
The shortest day of the month is April 1 with 12:52 hours of daylight; the longest day is April 30 with 14:25 hours of daylight.
The earliest sunrise is at 6:22am on April 30; the latest sunset is at 8:46pm on April 30; the latest sunrise is at 7:15am on April 1; the earliest sunset is at 8:07pm on April 1.
Daylight savings time is observed in 2012 but it neither starts nor ends in April, so the entire month is in daylight time.
The median cloud cover ranges from 79% (partly cloudy) to 87% (mostly cloudy). The trend is for the sky to be clearing with the median cloud cover decreasing by 8% from the start to the end of the month.
On April 15, a representative day, the sky is clear or mostly clear 32% of the time, partly cloudy 14% of the time, and mostly cloudy or overcast 54% of the time.
The average probability that some form of precipitation will be observed in a given day is 53%, with little variation over the course of the month.
Throughout April, the most common forms of precipitation are light rain, light snow, and moderate rain.
Light rain is the most severe precipitation observed during 40% of those days with precipitation. It is most likely around April 30, when it is observed during 24% of all days.
Light snow is the most severe precipitation observed during 29% of those days with precipitation. It is most likely around April 1, when it is observed during 22% of all days.
Moderate rain is the most severe precipitation observed during 18% of those days with precipitation. It is most likely around April 30, when it is observed during 11% of all days.
The likelihood of snow falling is highest around April 1, occurring in 26% of days.
Accumulation at this location in April is extremely unlikely. The chances of there being snow on the ground are highest around April 1, occurring 5% of the time.
The snow is typically at its deepest on April 17, with a median depth of 0.7"; the depth exceeds 0.8" only one year out of ten.
The relative humidity typically ranges from 34% (comfortable) to 89% (very humid) over the course of a typical April, rarely dropping below 20% (dry) and reaching as high as 100% (very humid).
The air is driest around April 22, at which time the relative humidity drops below 42% (comfortable) three days out of four; it is most humid around April 1, rising above 84% (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 April, the dew point typically varies from 22°F (dry) to 38°F (dry) and is rarely below 14°F (dry) or above 47°F (dry).
Over the course of April typical wind speeds vary from 0 mph to 17 mph (calm to moderate breeze), rarely exceeding 23 mph (fresh breeze).
The highest average wind speed of 7 mph (light breeze) occurs around April 19, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 7 mph (light breeze) occurs around April 3, at which time the average daily maximum wind speed is 16 mph (moderate breeze).