This report describes the typical weather at the Gibraltar Airport (Gibraltar) 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.
Gibraltar has a mediterranean climate with dry hot summers and mild winters. The area within 25 mi of this station is covered by oceans and seas (56%), grasslands (20%), shrublands (18%), croplands (3%), and forests (2%).
The month of September is characterized by falling daily high temperatures, with daily highs decreasing from 81°F to 75°F over the course of the month, exceeding 86°F or dropping below 71°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 1:05 hours, implying an average day-over-day decrease of 2.2 minutes.
The shortest day of the month is September 30 with 11:51 hours of daylight; the longest day is September 1 with 12:55 hours of daylight.
The earliest sunrise is at 7:53am on September 1; the latest sunset is at 8:49pm on September 1; the latest sunrise is at 8:16am on September 30; the earliest sunset is at 8:06pm 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 30% (mostly clear) to 45% (partly cloudy). The trend is for the sky to be becoming cloudier with the median cloud cover increasing by 15% from the start to the end of the month.
On September 1, the clearest day of the month, the sky is clear, mostly clear, or partly cloudy 78% of the time, and overcast or mostly cloudy 14% of the time.
On September 30, the cloudiest day of the month, the sky is overcast, mostly cloudy, or partly cloudy 49% of the time, and clear or mostly clear 45% 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 27% of days. Precipitation is least likely around September 1, occurring in 14% of days.
Throughout September, the most common forms of precipitation are moderate rain, thunderstorms, and light rain.
Moderate rain is the most severe precipitation observed during 55% of those days with precipitation. It is most likely around September 30, when it is observed during 16% of all days.
Thunderstorms are the most severe precipitation observed during 22% of those days with precipitation. They are most likely around September 29, when it is observed during 5% of all days.
Light rain is the most severe precipitation observed during 17% of those days with precipitation. It is most likely around September 28, when it is observed during 4% 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 56% (mildly humid) to 91% (very humid) over the course of a typical September, rarely dropping below 35% (comfortable) and reaching as high as 100% (very humid).
The air is driest around September 2, at which time the relative humidity drops below 71% (humid) three days out of four; it is most humid around September 29, rising above 88% (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 57°F (comfortable) to 68°F (muggy) and is rarely below 49°F (dry) or above 72°F (very muggy).
Over the course of September typical wind speeds vary from 4 mph to 17 mph (light breeze to moderate breeze), rarely exceeding 23 mph (fresh breeze).
The highest average wind speed of 11 mph (gentle breeze) occurs around September 5, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 11 mph (gentle breeze) occurs around September 26, at which time the average daily maximum wind speed is 17 mph (moderate breeze).