With a population of around 9,300, Monmouth sits in Illinois, United States. The city operates in the Central Time Zone.
In 2025, Monmouth recorded an average annual temperature of 53°F. The hottest temperatures reached 96°F in May; the coolest were -9°F in January. Total precipitation for the year was 29 inches, with the wettest month being July. Snowfall for the year totaled approximately 8 inches.
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