Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September is marked by a subtle drop in average high-temperatures, transitioning from a moderately hot 80.4°F (26.9°C) in August to a pleasant 72.7°F (22.6°C). An average low-temperature of 56.5°F (13.6°C) is observed during the September nights.Humidity
The average relative humidity in September is 76%.Rainfall
September is the month with the least rainfall. Rain falls for 11.8 days and accumulates 1.5" (38mm) of precipitation.Snowfall
In Mattapan, snow does not fall in May through September.Daylight
In September, the average length of the day is 12h and 28min.On the first day of September, sunrise is at 6:10 am and sunset at 7:17 pm. On the last day of the month, sunrise is at 6:41 am and sunset at 6:27 pm EDT.
Sunshine
In Mattapan, the average sunshine in September is 8.4h.UV index
In Mattapan, Massachusetts, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.Note: The UV index of 4 in September translates into these instructions:
Put precautions into practice - Guidance to elude sunburn is provided. Direct exposure to the Sun during its peak hours around mid-day should be minimized for safety. 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
What are September temperatures?
What is the average humidity in September?
What is the driest month?
How much does it rain in September?
When it does not snow?
Does it snow in September?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
How high is the UV index in September?
Average temperature in September
Mattapan, MA
- Average high temperature in September: 72.7°F
The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (33.6°F).
- Average low temperature in September: 56.5°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (21.9°F).
Average pressure in September
Mattapan, 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 (29.93"Hg).
Average wind speed in September
Mattapan, MA
- Average wind speed in September: 6.5mph
The windiest month (with the highest average wind speed) is January (9.5mph).
The calmest month (with the lowest average wind speed) is August (6mph).
Average humidity in September
Mattapan, 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
Mattapan, MA
- Average rainfall in September: 1.5"
The wettest month (with the highest rainfall) is December (2.95").
The driest month (with the least rainfall) is September (1.5").
Average rainfall days in September
Mattapan, MA
- Average rainfall days in September: 11.8 days
The month with the highest number of rainy days is July (15.8 days).
The months with the least rainy days are January and February (7.8 days).
Average snowfall in September
Mattapan, MA
- Average snowfall in September: 0"
The month with the highest snowfall is March (5.24").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Mattapan, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (8.2 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Mattapan, MA
- Average daylight in September: 12h and 3min
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 12min).
- Average sunshine in September: 8h and 2min
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
Mattapan, MA
- Average sunshine days in September: 15.8 days
The month with the most sunshine days is November (18 days).
The month with the least sunshine days is April (13.2 days).
Average UV index in September
Mattapan, 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
Mattapan, MA
- Average cloud cover in September: 37
The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 33).
Average visibility in September
Mattapan, 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).
Mattapan, Massachusetts, USA
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