O'Fallon, Illinois, United States of America: What to pack, what to wear, and when to go [2021]

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Traveling to O'Fallon, Illinois, United States of America? If you're planning to go to O'Fallon, we have some important information about when to go, what to wear, and what to pack.

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When to go to O'Fallon, Illinois, United States of America

Based on the climate and weather in O'Fallon, the best time to go is September. See below for details.

Important esssentials for O'Fallon, Illinois, United States of America

Here are some general tips on what to wear in O'Fallon, as well as several items to remember to pack when traveling there.

What to wear/what to pack for O'Fallon, Illinois, United States of America by month

January

January in O'Fallon can be brisk. Temperatures average in the high 30s F (single digits C) during the day. It rains regularly and snows once in a while.

What to wear/what to pack:

February

February in this region is brisk. Temperatures average in the 40s F (single digits C) during the day. It rains regularly.

What to wear/what to pack:

March

Traveling to O'Fallon in March, you will notice that it is crisp and somewhat rainy. Expect it to rain about a third of the time. Daytime temperatures are in the 50s F (low 10s C).

What to wear/what to pack:

April

April in O'Fallon is mild and somewhat rainy. The average overnight temperatures in the area are in the low 40s F (single digits C), with a few days below 32 F (single digits C).

It tends to rain 5-10 days this month. With the colder weather comes lower humidity, which is in the 40% to 50% range on average.

What to wear/what to pack:

  • Light jacket or fleece
  • Pants or jeans
  • Standard footwear
  • Dresses
  • Long skirts
  • Socks
  • Long sleeve shirts or blouses
  • A high quality rain poncho to wear over your jacket will avoid travel headaches by protecting your coat. We like this one.
  • rainy weather makes rubber rain boots a must; these boots are well-suited for stormy weather:
  • An umbrella this one #random{{designed|made|built} for storms.
  • A waterproof luggage cover so your belongings don't get wet. Even the finest luggage can let water in. We recommend: this one

May

In May, O'Fallon is warm and somewhat rainy. Temperatures routinely are in the 70s F (mid 20s C) and regularly jump into the low 80s F (high 20s C) range. At night, lows are in the low 50s F (low 10s C).

This is also a rainy time for O'Fallon, with several of the days of the month having rain. In May, humidity reaches as high as 60%.

What to wear/what to pack:

June

If you visit O'Fallon during June, you might see that it is extremely warm. Temperatures tend to hover around the 80s F (high 20s C) during the day, while at night they can dip into the low 60s F (high 10s C).

Humidity is generally between 50 and 60% during the day. In terms of precipitation, you can expect it to rain a bit less than half of the time.

What to wear/what to pack:

July

If you go to O'Fallon in July, you will notice that it is extremely hot. Expect it to rain a bit less than half of the time. Daytime temperatures are in the high 80s F (low 30s C).

What to wear/what to pack:

August

If you go to O'Fallon in August, you will notice that it is really hot. Expect it to rain regularly. Daytime temperatures are in the high 80s F (low 30s C).

What to wear/what to pack:

September

If you visit O'Fallon during September, you might see that it is hot. Temperatures tend to hover around the low 80s F (high 20s C) during the day, while at night they can dip into the 50s F (low 10s C).

Humidity is generally between 50 and 60% during the day. In terms of precipitation, you can expect it to rain 5-10 days this month.

What to wear/what to pack:

October

If you are traveling to O'Fallon in October, you will notice that it is mild. Expect it to rain 5-10 days this month. Daytime temperatures are in the high 60s F (low 20s C).

What to wear/what to pack:

  • Pants or jeans
  • Dresses
  • Light jacket or fleece
  • Long skirts
  • Long sleeve shirts or blouses
  • Standard footwear
  • Socks
  • A durable rain poncho to wear over your jacket will help avoid loads of aggrevation by protecting your coat. We like this one.
  • stormy weather makes rubber rain boots essential; these boots are well-suited for stormy weather:
  • An umbrella this one #random{{designed|made|built} for bad weather.
  • A waterproof luggage cover so your stuff stay dry. The best luggage can let rain in. We suggest: this one

November

November in O'Fallon is relatively cool. The rain can amount to several inches/centimeters.

During this time, temperatures average in the 40s F (single digits C) to 50s F (low 10s C), although night temperatures can dip into the low 30s F (single digits C).

What to wear/what to pack:

December

December in O'Fallon is brisk. The average overnight temperatures in the area are in the 20s F (single digits below 0 C).

It tends to rain 5-10 days this month. But the colder weather doesn't bring low humidity, which is in the 60% to 70% range on average.

What to wear/what to pack:

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