With a population of around 9,300, Monmouth sits in Illinois, United States. The city operates in the Central Time Zone.
Recent weather here gives a sense of typical conditions: in 2025, Monmouth recorded a mean annual temperature of 53°F, ranging from -9°F lows in January to 96°F highs in May, with about 29 inches of precipitation across the year.
View historical weather for Monmouth · More cities in Illinois