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 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 the warmest month, exhibiting average temperatures of 79°F (26.1°C) at the peak and 76.1°F (24.5°C) at the base.Humidity
In September, the average relative humidity is 77%.Rainfall
The month with the least rainfall is September, when the rain falls for 8.1 days and typically collects 0.43" (11mm) of precipitation.Snowfall
The only month with snowfall is September. September has the most snowfall days of the year. Snow falls for 0.1 days.Daylight
In September, the average length of the day is 12h and 15min.On the first day of September, sunrise is at 6:09 am and sunset at 6:40 pm. On the last day of the month, sunrise is at 6:16 am and sunset at 6:13 pm HST.
Sunshine
The average sunshine in September is 9.5h.UV index
September is the month with the highest UV index, with an average maximum UV index of 7. A UV Index estimate of 6 to 7 represents a high health hazard from unprotected exposure to Sun's UV rays for the average person.Note: In September, a regular UV index of 7 translates into these guidelines:
Persist in precautions and follow sun safety policies. Keeping sunburn at bay is imperative. Limit your exposure to the sun's UV radiation, which is strongest between 10 a.m. and 4 p.m., and note that parasols or canopies may not provide full sun protection. Limit sun-induced ocular harm with sunglasses that feature UVA and UVB filtration. On your guard! Snow's reflection can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the warmest months?
What is the average September temperature?
What is the average humidity in September?
What is the driest month?
How much does it rain in September?
When does it snow the most?
When does it start snowing?
What is the average length of the day in September?
When are sunrise and sunset in September?
How many hours of sunshine does Haiku have in September?
What is the month with the highest UV index?
What is the UV index reading in September?
Average temperature in September
Haiku, HI
- Average high temperature in September: 79°F
The warmest month (with the highest average high temperature) is September (79°F).
The month with the lowest average high temperature is March (72.9°F).
- Average low temperature in September: 76.1°F
The month with the highest average low temperature is September (76.1°F).
The coldest month (with the lowest average low temperature) is March (69.8°F).
Average pressure in September
Haiku, HI
- Average pressure in September: 29.97"Hg
The month with the highest atmospheric pressure is April (30.06"Hg).
The months with the lowest atmospheric pressure are September and October (29.97"Hg).
Average wind speed in September
Haiku, HI
- Average wind speed in September: 12.6mph
The windiest month (with the highest average wind speed) is June (14.4mph).
The calmest month (with the lowest average wind speed) is January (10.9mph).
Average humidity in September
Haiku, HI
- Average humidity in September: 77%
The months with the highest relative humidity are July and August (78%).
The months with the lowest relative humidity are January and February (76%).
Average rainfall in September
Haiku, HI
- Average rainfall in September: 0.43"
The wettest month (with the highest rainfall) is October (2.17").
The driest month (with the least rainfall) is September (0.43").
Average rainfall days in September
Haiku, HI
- Average rainfall days in September: 8.1 days
The month with the highest number of rainy days is March (14.1 days).
The month with the least rainy days is September (8.1 days).
Average snowfall days in September
Haiku, HI
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is September (0.1 days).
The months with the least snowfall days are January, February, March, April, May, June, July, August, October, November and December (0 days).
Average daylight in September /
Average sunshine in September
Haiku, HI
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 13h and 24min).
The month with the shortest days is December (Average daylight: 10h and 54min).
- Average sunshine in September: 9h and 3min
The months with the most sunshine are June and July (Average sunshine: 11h and 18min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in September
Haiku, HI
- Average sunshine days in September: 15.5 days
The month with the most sunshine days is January (16.8 days).
The month with the least sunshine days is November (11.2 days).
Average UV index in September
Haiku, HI
- Average UV index in September: 7
The month with the highest UV index is September (UV index 7).
The months with the lowest UV index are January, February, March, April, May, June, July, August, October, November and December (UV index 6).
Average cloud cover in September
Haiku, HI
- Average cloud cover in September: 23
The month with the most cloud cover is March (Cloud cover 33).
The month with the least cloud cover is September (Cloud cover 23).
Average visibility in September
Haiku, HI
- 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).
Haiku, Hawaii, USA
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