Weather forecast for 10 days
O'Fallon, MO

On Sunday, in O'Fallon, moderately clouded weather is also expected.
The temperature is forecasted to vary between a maximum of a hot 89.6°F (32°C) and a minimum of an agreeable 68°F (20°C).
The maximum heat index, which represents the influence of relative humidity on air temperature, is evaluated at a sweltering 98.6°F (37°C). Take into consideration that the heat index values are calculated for shade and light wind conditions. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees.
It will be hotter, and the highest temperature will be more in line with June's average maximum of 83.8°F (28.8°C) than May's of 74.5°F (23.6°C).
Sunrise will be at 5:46 am and sunset at 8:12 pm; tomorrow's daylight will last for 14h and 26min.

The weather will be unstable for the next ten days, and a mix of stormy, cloudy, sunny and rainy weather is predicted.
Rainfall is expected on Tuesday, Wednesday, Friday through next Monday. With moderate precipitation of 0.51" (13mm), most rainfall is expected on next Monday.
Temperature fluctuation will be substantial in the next ten days. The highest temperature will vary between 77°F (25°C) and 91.4°F (33°C), while the lowest nightly temperature fluctuation will be also considerable, as the lowest temperature will be between 57.2°F (14°C) and 69.8°F (21°C).
Tuesday will be the hottest day, with a maximum temperature of 91.4°F (33°C); Wednesday and next Sunday, with the highest temperature of 77°F (25°C), will be the coldest days.
Taking the humidity into consideration, the maximum feel-like temperature may increase and vary between 77°F (25°C) and a very hot 100.4°F (38°C).