September weather forecast
San Luis, AZ

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Weather in September

September in San Luis, Arizona sees temperatures easing from summer's peak to slightly cooler digits. With limited rainfall and a comparatively low relative humidity, the city maintains an arid environment. Changes in temperature point towards the onset of the fall season. Though the weather remains hot, evening temperatures provide some relief from high daytime temperatures. To sum it up, September represents a step towards a more comfortable climate after the dry and hot summer.

Temperature

Transition into September subtly marks a drop in the average high-temperature, moderately moving from a blisteringly hot 105.8°F (41°C) in August to a sweltering 99.7°F (37.6°C). During September, the nighttime temperature averages to a warm 80.6°F (27°C).

Humidity

In September, the average relative humidity is 30%.

Rainfall

In San Luis, in September, during 3.3 rainfall days, 0.24" (6mm) of precipitation is typically accumulated. Throughout the year, there are 25 rainfall days, and 2.24" (57mm) of precipitation is accumulated.

Daylight

In September, the average length of the day is 12h and 21min.
On the first day of September, sunrise is at 6:14 am and sunset at 7:03 pm. On the last day of the month, sunrise is at 6:33 am and sunset at 6:24 pm MST.

Sunshine

In San Luis, the average sunshine in September is 9.8h.

UV index

June through September, with an average maximum UV index of 8, are months with the highest UV index. A UV Index estimate of 8 to 10 represents a very high health hazard from unsafe exposure to UV radiation for ordinary individuals.
Note: In September, the maximum UV index of 8 suggests these recommendations:
Take all necessary measures. Eyes and skin are at risk if left unprotected. 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. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.

Frequently asked questions

How hot does it get in September?

During September, San Luis experiences an average high-temperature of 99.7°F (37.6°C) and a low-temperature of 80.6°F (27°C).

What is the average humidity in September?

In September, the average relative humidity is 30%.

How much does it rain in September?

In San Luis, in September, during 3.3 rainfall days, 0.24" (6mm) of precipitation is typically accumulated.

How many hours of daylight does San Luis have in September?

In San Luis, the average day length in September is 12h and 21min.

When are sunrise and sunset in September?

In September, on the first day of the month, sunrise is at 6:14 am and sunset at 7:03 pm. On the last day of the month, sunrise is at 6:33 am and sunset at 6:24 pm MST.

How many hours of sunshine does San Luis have in September?

In San Luis, the average sunshine duration in September is 9.8h.

What are the months with the highest UV index?

June through September, with an average maximum UV index of 8, are months with the highest UV index.

What is the UV index reading in September?

In San Luis, the average daily maximum UV index in September is 8. A UV Index of 8 to 10 symbolizes a very high hazard to health from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
San Luis, AZ

Average temperature in September - San Luis, AZ
  • Average high temperature in September: 99.7°F

The warmest month (with the highest average high temperature) is July (106.2°F).
The month with the lowest average high temperature is December (67.1°F).

  • Average low temperature in September: 80.6°F

The month with the highest average low temperature is August (86.2°F).
The coldest month (with the lowest average low temperature) is December (50.5°F).

Average pressure in September
San Luis, AZ

Average pressure in September - San Luis, AZ
  • Average pressure in September: 29.79"Hg

The month with the highest atmospheric pressure is January (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.75"Hg).

Average wind speed in September
San Luis, AZ

Average wind speed in September - San Luis, AZ
  • Average wind speed in September: 6.9mph

The windiest month (with the highest average wind speed) is July (8.5mph).
The calmest month (with the lowest average wind speed) is November (6.7mph).

Average humidity in September
San Luis, AZ

Average humidity in September - San Luis, AZ
  • Average humidity in September: 30%

The month with the highest relative humidity is December (38%).
The month with the lowest relative humidity is June (23%).

Average rainfall in September
San Luis, AZ

Average rainfall in September - San Luis, AZ
  • Average rainfall in September: 0.24"

The wettest month (with the highest rainfall) is July (0.39").
The driest month (with the least rainfall) is May (0").

Average rainfall days in September
San Luis, AZ

Average rainfall days in September - San Luis, AZ
  • Average rainfall days in September: 3.3 days

The month with the highest number of rainy days is July (5.1 days).
The month with the least rainy days is May (0.3 days).

Average daylight in September /
Average sunshine in September
San Luis, AZ

Average daylight in September / Average sunshine in September - San Luis, AZ
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 6min).

  • Average sunshine in September: 9h and 5min

The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 7h and 6min).

Average sunshine days in September
San Luis, AZ

Average sunshine days in September - San Luis, AZ
  • Average sunshine days in September: 26.1 days

The month with the most sunshine days is May (30.4 days).
The month with the least sunshine days is July (24.3 days).

Average UV index in September
San Luis, AZ

Average UV index in September - San Luis, AZ
  • Average UV index in September: 8

The months with the highest UV index are June, July, August and September (UV index 8).
The month with the lowest UV index is December (UV index 4).

Average cloud cover in September
San Luis, AZ

Average cloud cover in September - San Luis, AZ
  • Average cloud cover in September: 8

The month with the most cloud cover is December (Cloud cover 18).
The month with the least cloud cover is June (Cloud cover 5).

Average visibility in September
San Luis, AZ

Average visibility in September - San Luis, AZ
  • 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).

San Luis, Arizona, USA

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