For those who are wondering what the weather is like in September. The water temperature in the Welland Recreational Waterway on September 20, 2013 was 21C or 69.8F

Historical Monthly Averages For September In Niagara Falls

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 Niagara Falls.

Temperature

Throughout the month of September daytime temperatures will generally reach highs of around 24°C that’s about 75°F. At night the average minimum temperature drops down to around 12°C, that’s 53°F.
In recent times the highest recorded temperature in September has been 34°C that’s 93°F, with the lowest recorded temperature -1°C, about 30°F.

Relative Humidity

The average daily relative humidity for September is around 72%.

Heat Index

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).

Precipitation

The average monthly amount of precipitation has been recorded at around 77 mm, that’s 3 inches. Throughout the month you can expect to see rain or drizzle falling on 12 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 8 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.

Source: My Weather