This report describes the typical weather at the Niagara Falls International Airport (Niagara Falls, New York, United States) weather station over the course of an average September. It is based on the historical records from 1993 to 2012. Earlier records are either unavailable or unreliable.
Niagara Falls, New York has a humid continental climate with hot summers and no dry season. The area within 25 mi of this station is covered by grasslands (43%), oceans and seas (28%), forests (16%), and built-up areas (11%).
The month of September is characterized by rapidly falling daily high temperatures, with daily highs decreasing from 77°F to 66°F over the course of the month, exceeding 84°F or dropping below 56°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 1:23 hours, implying an average day-over-day decrease of 2.8 minutes.
The shortest day of the month is September 30 with 11:46 hours of daylight; the longest day is September 1 with 13:09 hours of daylight.
The earliest sunrise is at 6:41am on September 1; the latest sunset is at 7:49pm on September 1; the latest sunrise is at 7:13am on September 30; the earliest sunset is at 6:58pm 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 68% (partly cloudy) to 76% (partly cloudy). The trend is for the sky to be becoming cloudier with the median cloud cover increasing by 7% from the start to the end of the month.
On September 15, a representative day, the sky is clear or mostly clear 28% of the time, partly cloudy 18% of the time, and mostly cloudy or overcast 53% 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 49% of days. Precipitation is least likely around September 13, occurring in 45% of days.
Throughout September, the most common forms of precipitation are light rain, thunderstorms, and moderate rain.
Light rain is the most severe precipitation observed during 47% of those days with precipitation. It is most likely around September 29, when it is observed during 25% of all days.
Thunderstorms are the most severe precipitation observed during 23% of those days with precipitation. They are most likely around September 1, when it is observed during 14% of all days.
Moderate rain is the most severe precipitation observed during 18% of those days with precipitation. It is most likely around September 28, when it is observed during 10% 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 51% (mildly humid) to 95% (very humid) over the course of a typical September, rarely dropping below 37% (comfortable) and reaching as high as 100% (very humid).
The air is driest around September 1, at which time the relative humidity drops below 59% (mildly humid) three days out of four; it is most humid around September 19, rising above 92% (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 43°F (dry) to 63°F (mildy humid) and is rarely below 34°F (dry) or above 70°F (muggy).
The time of the month between September 1 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 15 mph (calm to moderate breeze), rarely exceeding 22 mph (fresh breeze).
The highest average wind speed of 9 mph (gentle breeze) occurs around September 29, at which time the average daily maximum wind speed is 15 mph (moderate breeze).
The lowest average wind speed of 8 mph (gentle breeze) occurs around September 1, at which time the average daily maximum wind speed is 14 mph (moderate breeze).