September weather forecast
Merrillville, IN

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Weather in September

September marks the start of fall in Merrillville with a gradual decrease in daylight hours from 13.8 in August to 12.5. The transition from summer to fall is subtle with average high temperatures decreasing to 73.9°F (23.3°C), making it a pleasant time to visit the city. The waning days of summer fuse with the emerging brisk fall climate, rendering a unique beauty to the locale. The season's change ushers in the time for fall festivities and the city's natural autumn landscape becomes a sight to behold.

Temperature

The shift from August to September includes a minor decrease in the average high-temperature, lightly dropping from 79.5°F (26.4°C) to a still warm 73.9°F (23.3°C). September in Merrillville is noted for a mean low-temperature of 57.7°F (14.3°C).

Humidity

In September, the average relative humidity in Merrillville is 76%.

Rainfall

In Merrillville, Indiana, during September, the rain falls for 12.7 days and regularly aggregates up to 1.85" (47mm) of precipitation. In Merrillville, during the entire year, the rain falls for 146.6 days and collects up to 23.31" (592mm) of precipitation.

Snowfall

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

Daylight

In Merrillville, Indiana, the average length of the day in September is 12h and 28min.
On the first day of the month, sunrise is at 6:16 am and sunset at 7:21 pm. On the last day of September, in Merrillville, sunrise is at 6:45 am and sunset at 6:32 pm CDT.

Sunshine

The average sunshine in September is 8.3h.

UV index

In Merrillville, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for the average person.
Note: The daily high UV index of 4 during September translates into the following recommendations:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. The midday Sun can be dangerous due to its intense radiation; always find shade and reduce exposure. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun.

Frequently asked questions

What is the temperature in September in Merrillville?

The average high-temperature and low-temperature in Merrillville, Indiana, during September are 73.9°F (23.3°C) and 57.7°F (14.3°C) respectively. The average heat index (a.k.a. 'felt air temperature', 'feels like'), which represents the influence of relative humidity on air temperature, in July is calculated to be 87.8°F (31°C).

What is the average humidity in September in Merrillville?

In Merrillville, Indiana, the average relative humidity in September is 76%.

How many days does it rain in September in Merrillville?

In Merrillville, Indiana, in September, it is raining for 12.7 days, with typically 1.85" (47mm) of accumulated precipitation.

When it does not snow in Merrillville?

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

Does it snow in Merrillville in September?

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

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

The average day length in September in Merrillville is 12h and 28min.

What time are sunrise and sunset in September in Merrillville?

In September, on the first day of the month, sunrise is at 6:16 am and sunset at 7:21 pm. On the last day of the month, sunrise is at 6:45 am and sunset at 6:32 pm CDT.

How many hours of sunshine does Merrillville have in September?

In Merrillville, the average sunshine duration in September is 8.3h.

How high is the UV index in September in Merrillville?

In Merrillville, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium health risk from exposure to Sun's UV rays.
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
Merrillville, IN

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

The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is January (30°F).

  • Average low temperature in September: 57.7°F

The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (18.9°F).

Average pressure in September
Merrillville, IN

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

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

Average wind speed in September
Merrillville, IN

Average wind speed in September - Merrillville, IN
  • Average wind speed in September: 7.3mph

The windiest month (with the highest average wind speed) is January (10.3mph).
The calmest month (with the lowest average wind speed) is August (6.3mph).

Average humidity in September
Merrillville, IN

Average humidity in September - Merrillville, IN
  • Average humidity in September: 76%

The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is October (73%).

Average rainfall in September
Merrillville, IN

Average rainfall in September - Merrillville, IN
  • Average rainfall in September: 1.85"

The wettest month (with the highest rainfall) is June (3.15").
The driest month (with the least rainfall) is November (1.06").

Average rainfall days in September
Merrillville, IN

Average rainfall days in September - Merrillville, IN
  • Average rainfall days in September: 12.7 days

The month with the highest number of rainy days is July (17.6 days).
The month with the least rainy days is February (5.3 days).

Average snowfall in September
Merrillville, IN

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

The month with the highest snowfall is February (3.5").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in September
Merrillville, IN

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

The month with the highest number of snowfall days is January (12.4 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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

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

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).

  • Average sunshine in September: 8h and 2min

The month with the most sunshine is August (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 30min).

Average sunshine days in September
Merrillville, IN

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

The month with the most sunshine days is November (17.4 days).
The month with the least sunshine days is July (10.2 days).

Average UV index in September
Merrillville, IN

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

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

Average cloud cover in September
Merrillville, IN

Average cloud cover in September - Merrillville, IN
  • Average cloud cover in September: 35

The month with the most cloud cover is January (Cloud cover 64).
The month with the least cloud cover is August (Cloud cover 32).

Average visibility in September
Merrillville, IN

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

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

Merrillville, Indiana, USA

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