September weather forecastPoipu, HI
September
Weather in September
The weather in September takes an interesting turn when rainfall decreases to 1.54" (39mm), the lowest in the second half of the year. Temperatures sustain the hot summer trend, while the daylight starts receding gradually. Even though cloud cover reduces from August to September, humidity levels maintain stability. The wind also drops a notch, explicitly supporting outdoor activities around the city. The UV index steps into the higher bracket, highlighting the need for sunblock during the daytime.Temperature
Poipu experiences its highest average temperatures in September, reaching a peak of 79.7°F (26.5°C) and a minimum of 75.9°F (24.4°C).Humidity
In September, the average relative humidity is 76%.Rainfall
In Poipu, in September, it is raining for 18.7 days, with typically 1.54" (39mm) of accumulated precipitation. In Poipu, during the entire year, the rain falls for 218.4 days and collects up to 22.13" (562mm) of precipitation.Daylight
In September, the average length of the day in Poipu is 12h and 16min.On the first day of September in Poipu, sunrise is at 6:21 am and sunset at 6:53 pm. On the last day of the month, sunrise is at 6:29 am and sunset at 6:25 pm HST.
Sunshine
The average sunshine in September is 8.7h.UV index
September is the month with the highest UV index, with an average maximum UV index of 7. A UV Index value of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV rays for the average person.Note: During September, 7 as the daily maximum UV index converts into the following advice:
Avoid overexposure. Fair-skinned individuals can burn in under 20 minutes. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Poipu, HI
- Average high temperature in September: 79.7°F
The warmest month (with the highest average high temperature) is September (79.7°F).
The months with the lowest average high temperature are February and March (73.2°F).
- Average low temperature in September: 75.9°F
The month with the highest average low temperature is September (75.9°F).
The coldest month (with the lowest average low temperature) is February (68.5°F).
Average pressure in September
Poipu, HI
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is April (30.07"Hg).
The months with the lowest atmospheric pressure are September and October (29.98"Hg).
Average wind speed in September
Poipu, HI
- Average wind speed in September: 11.1mph
The windiest month (with the highest average wind speed) is July (12.3mph).
The calmest month (with the lowest average wind speed) is January (10mph).
Average humidity in September
Poipu, HI
- Average humidity in September: 76%
The months with the highest relative humidity are June, July, August, October and December (77%).
The month with the lowest relative humidity is January (75%).
Average rainfall in September
Poipu, HI
- Average rainfall in September: 1.54"
The wettest month (with the highest rainfall) is March (2.52").
The driest month (with the least rainfall) is April (1.3").
Average rainfall days in September
Poipu, HI
- Average rainfall days in September: 18.7 days
The month with the highest number of rainy days is August (21.1 days).
The month with the least rainy days is January (12.5 days).
Average daylight in September /
Average sunshine in September
Poipu, HI
- Average daylight in September: 12h and 18min
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 48min).
- Average sunshine in September: 8h and 42min
The month with the most sunshine is June (Average sunshine: 9h and 42min).
The month with the least sunshine is November (Average sunshine: 6h and 12min).
Average sunshine days in September
Poipu, HI
- Average sunshine days in September: 5.3 days
The month with the most sunshine days is January (12.8 days).
The month with the least sunshine days is August (2.9 days).
Average UV index in September
Poipu, 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
Poipu, HI
- Average cloud cover in September: 38
The month with the most cloud cover is March (Cloud cover 47).
The months with the least cloud cover are January and September (Cloud cover 38).
Average visibility in September
Poipu, 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).
