September weather forecast
River, IN

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Weather in September

September, the first month of the autumn in River, is also a moderately hot month, with an average temperature fluctuating between 55.6°F (13.1°C) and 73.9°F (23.3°C).

Temperature

September's arrival signals a moderate reduction in the average high-temperature, easing from 79.3°F (26.3°C) in August to a still moderately hot 73.9°F (23.3°C). River usually reports an average low-temperature of 55.6°F (13.1°C) during the month of September.

Humidity

In September, the average relative humidity in River, Indiana, is 79%.

Rainfall

In River, during September, the rain falls for 13.5 days and regularly aggregates up to 1.57" (40mm) of precipitation. Throughout the year, in River, there are 153.8 rainfall days, and 25" (635mm) of precipitation is accumulated.

Snowfall

In River, snow does not fall in May through September.

Daylight

In River, Indiana, the average length of the day in September is 12h and 27min.
On the first day of September, sunrise is at 7:09 am and sunset at 8:13 pm. On the last day of the month, sunrise is at 7:38 am and sunset at 7:25 pm EDT.

Sunshine

In September, the average sunshine is 8h.

UV index

In River, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for average individuals.
Note: An average maximum UV index of 4 in September leads to these recommendations:
Take necessary precautions - Suggestions to elude sunburn are provided. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. Tightly woven clothing, when worn loosely, shields effectively against the Sun.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature in River?

September temperatures vary between a high-temperature of 73.9°F (23.3°C) and a low-temperature of 55.6°F (13.1°C). The average heat index (a.k.a. 'real feel', 'feels like'), which takes the relative humidity and factors it into the air temperature reading, in July is calculated to be 86°F (30°C).

What is the average humidity in September in River?

In September, the average relative humidity is 79%.

How much does it rain in River in September?

In River, during September, the rain falls for 13.5 days and regularly aggregates up to 1.57" (40mm) of precipitation.

When it does not snow in River?

May through September are months without snowfall in River.

Does it snow in River in September?

In River, Indiana, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does River have in September?

In September, the average day length in River is 12h and 27min.

When is the sunrise / sunset in September in River?

In September, on the first day of the month, sunrise is at 7:09 am and sunset at 8:13 pm. On the last day of the month, sunrise is at 7:38 am and sunset at 7:25 pm EDT.

How many hours of sunshine does River have in September?

In River, Indiana, the average sunshine duration in September is 8h.

What is the UV index reading in September in River?

In River, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
River, IN

Average temperature in September - River, IN
  • Average high temperature in September: 73.9°F

The warmest month (with the highest average high temperature) is July (80.8°F).
The month with the lowest average high temperature is January (30.7°F).

  • Average low temperature in September: 55.6°F

The month with the highest average low temperature is July (64°F).
The coldest month (with the lowest average low temperature) is January (19.2°F).

Average pressure in September
River, IN

Average pressure in September - River, IN
  • Average pressure in September: 30.03"Hg

The months with the highest atmospheric pressure are January and November (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in September
River, IN

Average wind speed in September - River, IN
  • Average wind speed in September: 7mph

The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.2mph).

Average humidity in September
River, IN

Average humidity in September - River, IN
  • Average humidity in September: 79%

The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is October (75%).

Average rainfall in September
River, IN

Average rainfall in September - River, IN
  • Average rainfall in September: 1.57"

The wettest month (with the highest rainfall) is April (3.07").
The driest month (with the least rainfall) is February (1.42").

Average rainfall days in September
River, IN

Average rainfall days in September - River, IN
  • Average rainfall days in September: 13.5 days

The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is January (6.8 days).

Average snowfall in September
River, IN

Average snowfall in September - River, IN
  • Average snowfall in September: 0"

The month with the highest snowfall is February (3.27").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in September
River, IN

Average snowfall days in September - River, IN
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (13.4 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in September /
Average sunshine in September
River, IN

Average daylight in September / Average sunshine in September - River, IN
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in September: 8h and 0min

The month with the most sunshine is July (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 18min).

Average sunshine days in September
River, IN

Average sunshine days in September - River, IN
  • Average sunshine days in September: 14.5 days

The month with the most sunshine days is October (16 days).
The months with the least sunshine days are February and May (10.5 days).

Average UV index in September
River, IN

Average UV index in September - River, IN
  • Average UV index in September: 4

The month with the highest UV index is June (UV index 6).
The months with the lowest UV index are January, February, March, October, November and December (UV index 2).

Average cloud cover in September
River, IN

Average cloud cover in September - River, IN
  • Average cloud cover in September: 36

The month with the most cloud cover is January (Cloud cover 65).
The month with the least cloud cover is August (Cloud cover 33).

Average visibility in September
River, IN

Average visibility in September - River, IN
  • Average visibility in September: 6mi

The months with the highest visibility are February, March, April, May, June, July, September, October, November and December (6mi).
The months with the lowest visibility are January and August (5mi).

River, Indiana, USA

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