Country Overview For United States Of America
For Washington The wettest month for Washington
HISTORICAL MONTHLY AVERAGES FOR SEPTEMBER
The information presented below gives detailed historical monthly average weather conditions along with exceptional weather occurrences. To maintain relevance to current weather trends the displayed information has been calculated using data collected over the past two decades. The climate profile is taken from closest available data source to Hoover Dam.
Throughout the month of September daytime temperatures will generally reach highs of around 36°C that's about 96°F. At night the average minimum temperature drops down to around 21°C, that's 69°F.
In recent times the highest recorded temperature in September has been 42°C that's 108°F, with the lowest recorded temperature 12°C, about 54°F.
The average daily relative humidity for September is around 19%.
The Heat Index is a measure of how hot it feels when relative humidity is added to actual air temperature. From this a comfort level is calculated providing categories on how heat conditions might adversely affect someone.
Comfort Levels: Given average maximum temperatures and humidity levels generally you should not anticipate any discomfort from heat (see heat index for more information).
The average monthly amount of precipitation has been recorded at around 4 mm, that's 0 inches. Throughout the month you can expect to see rain or drizzle falling on 2 days of the month.
Estimated Hours of Sunshine per Day
We calculate sunshine hours per day using our past forecast data. For September expect the sun to shine for an average of 12 hours per day. This represents the average number of hours in the daytime that the sun is visible and not obscured by cloud e.g. the average number of hours the sun is actually out and shining. Note we calculate hours of sunshine per day using our past forecast data, not observation data, thus it is an estimate and not actual.
The average daily wind speed in September has been around 13 km/h, that’s the equivalent to about 8 mph, or 7 knots. In recent years the maximum sustained wind speed has reached 63 km/h, that’s the equivalent of around 39 mph, or 34 knots.
On average the month of September is not affected by foggy conditions.
YEARLY TRENDS: WEATHER AVERAGES & EXTREMES
The following charts show yearly weather trends with information on monthly weather averages and extremes.
The chart below plots the average high and low temperature for each month of the year. It also shows the maximum and minimum recorded temperatures.
The chart below plots the average monthly precipitation amount.
The chart below plots the average number of days in any month that you can expect to see rain falling.
The chart below plots the average number of days in any month that you can expect to see snow falling.
The chart below plots the average daily wind speed you can expect for any month. It also shows the maximum recorded sustained wind speed for each month.