September weather forecast
Iona, ID

Weather in September

The first month of the autumn, September, is also a moderately hot month in Iona, Idaho, with average temperature fluctuating between 73.6°F (23.1°C) and 49.5°F (9.7°C).

Temperature

In September, the average high-temperature decreases, from 84.4°F (29.1°C) in August, to a still warm 73.6°F (23.1°C). The average low-temperature, in Iona, is 49.5°F (9.7°C).

Humidity

In Iona, the average relative humidity in September is 41%.

Rainfall

The wettest months are May and September, with an average 0.83" (21mm) of rainfall.

Snowfall

Months with snowfall in Iona are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, there are 54.4 snowfall days, and 16.89" (429mm) of snow is accumulated.

Daylight

In Iona, the average length of the day is 12.5h.

Sunshine

In September, the average sunshine in Iona is 10h.

UV index

The average daily maximum UV index in Iona is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from the exposure to the Sun's UV radiation for the ordinary person.
Note: In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against the skin and eye damage is obliged. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the average humidity in September in Iona?

In Iona, Idaho, the average relative humidity in September is 41%.

What is the rainiest month in Iona?

Months with the most rainfall are May and September, with an average 0.83" (21mm) of precipitation.

How many days does it rain in September in Iona?

In Iona, Idaho, in September, it is raining for 8.1 days, with typically 0.83" (21mm) of accumulated precipitation.

When does it start snowing in Iona?

September is the first month it typically snows in Iona. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow.

What is the average length of the day in September in Iona?

In Iona, Idaho, the average length of the day in September is 12.5h.

How long on average sun shines in September in Iona?

The average sunshine in September in Iona is 10h.

What is the UV index reading in September in Iona?

In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate health threat from the exposure to the Sun's UV radiation.

Average temperature in September
Iona, ID

Average temperature in September - Iona, ID
  • Average high temperature in September: 73.6°F

The warmest month (with the highest average high temperature) is July (86.2°F).
The month with the lowest average high temperature is December (27.9°F).

  • Average low temperature in September: 49.5°F

The month with the highest average low temperature is August (54.3°F).
The coldest month (with the lowest average low temperature) is January (14.2°F).

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Average pressure in September
Iona, ID

Average pressure in September - Iona, ID
  • Average pressure in September: 29.98"

The month with the highest atmospheric pressure is January (30.3").
The month with the lowest atmospheric pressure is June (29.91").

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Average wind speed in September
Iona, ID

Average wind speed in September - Iona, ID
  • Average wind speed in September: 7.6mph

The windiest month (with the highest average wind speed) is April (9mph).
The calmest month (with the lowest average wind speed) is January (5.8mph).

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Average humidity in September
Iona, ID

Average humidity in September - Iona, ID
  • Average humidity in September: 41%

The month with the highest relative humidity is January (90%).
The month with the lowest relative humidity is August (35%).

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Average rainfall in September
Iona, ID

Average rainfall in September - Iona, ID
  • Average rainfall in September: 0.83"

The wettest months (with the highest rainfall) are May and September (0.83").
The driest month (with the least rainfall) is July (0.35").

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Average rainfall days in September
Iona, ID

Average rainfall days in September - Iona, ID
  • Average rainfall days in September: 8.1 days

The month with the highest number of rainy days is May (10.7 days).
The month with the least rainy days is January (3.7 days).

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Average snowfall in September
Iona, ID

Average snowfall in September - Iona, ID
  • Average snowfall in September: 0.04"

The month with the highest snowfall is January (3.86").
Months with the least snowfall are June, July and August (0").

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Average snowfall days in September
Iona, ID

Average snowfall days in September - Iona, ID
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is December (12.9 days).
Months with the least snowfall days are June, July and August (0 days).

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Average daylight in September /
Average sunshine in September
Iona, ID

Average daylight in September / Average sunshine in September - Iona, ID
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.4h).
The month with the shortest days is December (Average daylight: 9h).

  • Average sunshine in September: 10h

The month with the most sunshine is July (Average sunshine: 11.8h).
The month with the least sunshine is January (Average sunshine: 4.7h).

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Average sunshine days in September
Iona, ID

Average sunshine days in September - Iona, ID
  • Average sunshine days in September: 19.4 days

The month with the most sunshine days is October (22.1 days).
The month with the least sunshine days is February (16.2 days).

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Average UV index in September
Iona, ID

Average UV index in September - Iona, ID
  • Average UV index in September: 4

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

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Average cloud cover in September
Iona, ID

Average cloud cover in September - Iona, ID
  • Average cloud cover in September: 16

Months with the most cloud cover are January and February (Cloud cover 51).
Months with the least cloud cover are July and August (Cloud cover 11).

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Average visibility in September
Iona, ID

Average visibility in September - Iona, ID
  • Average visibility in September: 6mi

Months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
Months with the lowest visibility are January and February (4mi).

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