Situated between Arkansas to its south and Iowa to its north, Missouri covers a land area of approximately 70,000 square miles. In the state’s southeastern corner, a sliver of land nicknamed the “boot heel” protrudes southward. Missouri’s landscape is mainly flat. The only exception are the Ozark Hills, rising to 1,800 feet in the southwest and south-central parts of the state, with their numerous lakes and streams attracting anglers and other nature enthusiasts. Missouri’s relatively mild climate means that outdoor aficionados can pursue their pastimes for a greater portion of the year than in more northerly states.
Missouri’s climate trends essentially run along a diagonal gradient. Northwestern Missouri is the coldest and driest part of the state, and the climate becomes warmer and more humid moving farther toward the southeast, with the boot heel possessing the highest average annual temperatures and precipitation totals. For example, Missouri’s northwestern-most counties have a mean annual temperature of 50 degrees Fahrenheit and receive around 35 inches of precipitation per year. But the boot heel counties have a mean annual temperature of about 60 degrees and receive nearly 50 inches of precipitation annually. The influence of opposite air masses causes this disparity – dry, cool continental air masses wield a greater influence in the northwest, while humid, subtropical air masses tend to dictate the weather farther southeast.
During summertime, hot, muggy air masses from the Gulf of Mexico drift northward into Missouri, dominating the weather patterns. Daytime highs during the hottest months, July and August, average between 87 and 90 statewide. Luckily, cold fronts originating in Canada sometimes make their way through, particularly in the northwest, provides brief respites from the otherwise sultry, steamy atmosphere. Precipitation in summer varies. Passing cold fronts can bring showers or thunderstorms. Sometimes high pressure systems stagnate, causing days or even weeks without rain, occasionally leading to droughts. On the other hand, remnants of tropical systems that strike Gulf coastal states can track into Missouri, especially the southern part of the state. They bring with them extremely heavy rainfall, which can sometimes last multiple days.
In wintertime, cold fronts regularly sweep across the state, bringing rain or snow and occasionally ice. Northern sections of Missouri typically receive just over 20 inches of snow annually, while the southeast receives less than 10 inches, since most precipitation there falls as rain. But even in the northern counties, snow doesn’t usually linger – any snowfall that has accumulated on the ground usually melts in a week or less. In terms of temperatures, it can actually become quite chilly in Missouri, especially in the northwest. Overnight lows dip into the teens after the passage of cold fronts, and sub-zero lows occur a few days each season. But such harsh cold snaps typically last only a couple days, and then temperatures moderate. Stretches of mild temperatures in the 40s and even 50s occur regularly.
Spring and Autumn
Temperatures in autumn lie between the two extremes of summer and winter. During these seasons, conditions may fluctuate rapidly, as the cool and dry continental air masses clash with the warm and humid Gulf of Mexico air masses. Large swings in temperature, such drops of 40 degrees after the passage of a cold front, aren’t uncommon. Spring sets in during March and April. The southeast usually experiences its last freeze in mid-March, while the last freeze in the northwest occurs in mid-April. In the fall, the first freezes occur in late October in the northwest, and late November in the southeast. The higher elevations of the Ozarks experience freeze dates more akin to those in the northwest. Severe thunderstorms are a regular occurrence each spring, especially in May, with some storms producing hail and, inevitably, tornadoes. And in the fall, as in the summer, remnants of tropical storms and hurricanes can produce extensive downpours.
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