Historical weather data, all-time temperature records, and monthly climate averages for Hannibal, MO. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Hannibal runs mild on paper — an average high of 59° and low of 38° — but the record books tell a wilder story. This date has swung from a brutal 20° in 1975 to a shirt-sleeve 89° in 2011, a 69-degree spread that captures Missouri's refusal to commit to spring. There's about a 1-in-3 chance of rain today historically, so keep an umbrella within reach.
Hannibal's weather has real teeth at both ends of the thermometer. The mercury once hit 114° in July 1954 and plunged to -21° in January 1985 — a jaw-dropping 135-degree range between the town's extremes. A single day in July 1949 dropped nearly 6 inches of rain, and a February 2011 snowstorm buried the city under 14.5 inches.
Hannibal follows a classic Midwest pattern: brutally cold winters, hot and humid summers, with spring as the wettest stretch. Highs bottom out around 34° in mid-January and peak near 88° in late July, while the third week of May is historically the soggiest, averaging over an inch of precipitation. If you're planning a visit, late September and early October offer a sweet spot — highs in the upper 60s with the worst of the heat and rain behind you.