This report describes the typical weather at the Galileo Galilei Airport (Pisa International Airport) (Pisa, Italy) weather station over the course of an average September. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
Pisa has a mediterranean climate with dry hot summers and mild winters. The area within 25 mi of this station is covered by croplands (47%), oceans and seas (39%), forests (11%), and shrublands (2%).
The month of September is characterized by falling daily high temperatures, with daily highs decreasing from 81°F to 74°F over the course of the month, exceeding 87°F or dropping below 67°F only one day in ten.
Over the course of September, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 1:26 hours, implying an average day-over-day decrease of 2.9 minutes.
The shortest day of the month is September 30 with 11:46 hours of daylight; the longest day is September 1 with 13:12 hours of daylight.
The earliest sunrise is at 6:42am on September 1; the latest sunset is at 7:53pm on September 1; the latest sunrise is at 7:15am on September 30; the earliest sunset is at 7:01pm on September 30.
Daylight saving time is observed in 2012 but it neither starts nor ends in September, so the entire month is in daylight time.
The median cloud cover ranges from 34% (mostly clear) to 43% (partly cloudy). The trend is for the sky to be becoming cloudier with the median cloud cover increasing by 8% from the start to the end of the month.
On September 15, a representative day, the sky is clear or mostly clear 51% of the time, partly cloudy 30% 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 September 30, occurring in 37% of days. Precipitation is least likely around September 1, occurring in 28% of days.
Throughout September, the most common forms of precipitation are thunderstorms, moderate rain, and light rain.
Thunderstorms are the most severe precipitation observed during 57% of those days with precipitation. They are most likely around September 21, when it is observed during 20% of all days.
Moderate rain is the most severe precipitation observed during 26% of those days with precipitation. It is most likely around September 30, when it is observed during 11% of all days.
Light rain is the most severe precipitation observed during 13% of those days with precipitation. It is most likely around September 30, when it is observed during 5% of all days.
Either snow is exceptionally unlikely to fall at this location in September or this station does not reliably report precipitation types.
The relative humidity typically ranges from 47% (comfortable) to 96% (very humid) over the course of a typical September, rarely dropping below 30% (comfortable) and reaching as high as 100% (very humid).
The air is driest around September 1, at which time the relative humidity drops below 55% (mildly humid) three days out of four; it is most humid around September 27, rising above 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 typical September, the dew point typically varies from 51°F (very comfortable) to 67°F (muggy) and is rarely below 42°F (dry) or above 72°F (very muggy).
The time of the month between September 8 and September 30 is the most comfortable, with dew points that are neither too dry nor too muggy.
Over the course of September typical wind speeds vary from 0 mph to 12 mph (calm to gentle breeze), rarely exceeding 19 mph (fresh breeze).
The highest average wind speed of 5 mph (light breeze) occurs around September 5, at which time the average daily maximum wind speed is 12 mph (gentle breeze).
The lowest average wind speed of 5 mph (light breeze) occurs around September 11, at which time the average daily maximum wind speed is 11 mph (gentle breeze).