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 signals a slight drop in average high-temperature, sliding from August's moderately hot 81°F (27.2°C) to a pleasant 73.2°F (22.9°C). In the month of September, Waltham experiences an average low-temperature of 56.3°F (13.5°C).Humidity
In September, the average relative humidity is 76%.Rainfall
September is the month with the least rainfall. Rain falls for 8.3 days and accumulates 0.35" (9mm) of precipitation.Snowfall
June through October are months without snowfall in Waltham, Massachusetts.Daylight
The average length of the day in September 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, in Waltham, sunrise is at 6:41 am and sunset at 6:27 pm EDT.
Sunshine
In September, the average sunshine in Waltham is 8.5h.UV index
In September, the average daily maximum UV index in Waltham is 4. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for ordinary individuals.Note: In September, the UV index of 4 transforms into the following advice:
Undertake precautions - Obligation exists to protect against skin and eye damage. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays.
Frequently asked questions
What is the usual temperature for Waltham in September?
What is the average humidity in September in Waltham?
What is the driest month in Waltham?
How much does it rain in Waltham in September?
When it does not snow in Waltham?
How many hours of daylight does Waltham have in September?
When is the sunrise / sunset in September in Waltham?
How long on average sun shines in September in Waltham?
What is the UV index intensity in September in Waltham?
Average temperature in September
Waltham, MA
- Average high temperature in September: 73.2°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.3°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 (21.6°F).
Average pressure in September
Waltham, 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
Waltham, 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
Waltham, 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
Waltham, MA
- Average rainfall in September: 0.35"
The wettest months (with the highest rainfall) are April and November (0.87").
The driest month (with the least rainfall) is September (0.35").
Average rainfall days in September
Waltham, MA
- Average rainfall days in September: 8.3 days
The month with the highest number of rainy days is July (12.4 days).
The month with the least rainy days is January (5.3 days).
Average snowfall in September
Waltham, MA
- Average snowfall in September: 0"
The month with the highest snowfall is December (1.14").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in September
Waltham, MA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (5.4 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Waltham, 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 6min).
- Average sunshine in September: 8h and 3min
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
Waltham, MA
- Average sunshine days in September: 19.4 days
The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is June (15.8 days).
Average UV index in September
Waltham, 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
Waltham, 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 32).
Average visibility in September
Waltham, 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).
Waltham, Massachusetts, USA
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