September weather forecastWatertown, MA
September
Weather in September
September, the first month of the autumn in Watertown, is still a pleasant month, with an average temperature varying between 73°F (22.8°C) and 56.3°F (13.5°C).Temperature
Watertown's progression into September involves a minor drop in the average high-temperature, slightly receding from a moderately hot 81°F (27.2°C) in August to a pleasant 73°F (22.8°C). Throughout the nights in September, an average low-temperature of 56.3°F (13.5°C) is noted.Humidity
The average relative humidity in September is 76%.Rainfall
The month with the least rainfall is September, when the rain falls for 6.6 days and typically collects 0.24" (6mm) of precipitation.Snowfall
June through October are months without snowfall.Daylight
In September, the average length of the day is 12h and 28min.On the first day of the month, sunrise is at 6:10 am and sunset at 7:18 pm. On the last day of September, sunrise is at 6:41 am and sunset at 6:27 pm EDT.
Sunshine
In September, the average sunshine in Watertown is 8.6h.UV index
In Watertown, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the ordinary person.Note: In September, the UV index of 4 transforms into the following advice:
Take precautions - Protection against skin and eye damage is obliged. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. Always opt for UVA and UVB-resistant sunglasses on radiant days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Watertown, MA
- Average high temperature in September: 73°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (33.6°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (64°F).
The coldest month (with the lowest average low temperature) is January (21.7°F).
Average pressure in September
Watertown, MA
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Watertown, MA
- Average wind speed in September: 6.3mph
The windiest month (with the highest average wind speed) is January (9.1mph).
The calmest month (with the lowest average wind speed) is August (5.8mph).
Average humidity in September
Watertown, MA
- Average humidity in September: 76%
The month with the highest relative humidity is February (78%).
The month with the lowest relative humidity is April (70%).
Average rainfall in September
Watertown, MA
- Average rainfall in September: 0.24"
The wettest month (with the highest rainfall) is November (0.67").
The driest month (with the least rainfall) is September (0.24").
Average rainfall days in September
Watertown, MA
- Average rainfall days in September: 6.6 days
The month with the highest number of rainy days is July (10.2 days).
The month with the least rainy days is February (4.1 days).
Average snowfall in September
Watertown, MA
- Average snowfall in September: 0"
The month with the highest snowfall is December (0.91").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in September
Watertown, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.9 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Watertown, MA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 8h and 36min
The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in September
Watertown, MA
- Average sunshine days in September: 21.4 days
The months with the most sunshine days are January and November (22.5 days).
The month with the least sunshine days is June (17.5 days).
Average UV index in September
Watertown, MA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover in September
Watertown, MA
- Average cloud cover in September: 36
The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 32).
Average visibility in September
Watertown, MA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
