Iowa experiences a humid continental climate (Köppen climate classification Dfa) with hot summers and cold winters. Missouri in the south, Nebraska in the west, South Dakota in the northwest, Minnesota in the north, Wisconsin in the northeast and Illinois in the east, bordering the state. Iowa lies in the far interior of the continent, and the majority of the state rests in a similar climatic zone. The near absence of high mountain ranges, decline in tree cover, and remoteness from major seas and oceans contribute to extreme seasonal variations in the weather.
Iowa, the Hawkeye state, mainly consists of prairie and savanna type grasslands, forests, and wetlands, although agriculture lands, pastures, and urban dwellings have replaced most of the original natural habitat. The state is short of towering mountain ranges. However, the landscape is uneven with many rolling hills, lakes such as Spirit Lake, West Okoboji Lake, East Okoboji Lake, and Clear Lake, and rivers such as the Mississippi, Missouri, Big Sioux, and Des Moines. Northeast Iowa consists of steep hills and valleys in contrast to the rest of the state.
Summer is hot and humid and usually the rainiest season of the year. Day temperatures are often in the 90°F (32.2°C) to 100°F (37.8°C) zone but rarely cross 100°F (37.8°C) in the peak of July. Nights are warm and regularly lie in the 60°F (15.6°C) to 65°F (18.3°C) range. Winter is severely cold as even the day temperatures frequently plummet below freezing, and the mercury column is not averse to display -20°F (-28.9°C) in January. Spring is a pleasant season with temperate weather but is wet and prone to thunderstorms and tornadoes. Autumn displays beautiful colors across the landscape, and the early fall period is quite enjoyable compared to the later when windy conditions frequently create spells of chilly weather.
Iowa registers 35" (889mm) of rain throughout the year, which sees uneven distribution between the seasons as summer alone records more than two-thirds of the annual precipitation in the state. January is usually the driest month in the state, while June is the wettest. Iowa often experiences flooding during the summer due to the rapid melting of snow and when the rainfall exceeds the average. Snowfall is frequent during the winter, but vast deposits rarely accumulate in short periods as an average of 30" (762mm) accumulates in the state. The Iowa sun is blazing during the summer, and the state receives 2686 hours of sunlight over the year.
The record high temperature for Iowa is 118°F (47.8°C), set in Keokuk on July 20, 1934, while the lowest recorded temperature is -47°F (-43.9°C), set in Elkader on February 3, 1996.
The best time to visit Iowa
Autumn is the best time to visit Iowa, during September and October, while late fall is cold and windy. The conditions are pleasant compared to the heat of summer and the cold of winter. Late spring is subject to thunderstorms, while summer experiences severe flooding many times. The middle part of spring around April is also an excellent time to visit Iowa. Summers tend to be hot and humid and the peak tourist season in Iowa, so traveling during the spring and fall is more economical than during the summer.
The worst time to visit Iowa
November to February is the worst time to visit Iowa as the state lies in the grip of severe cold weather and extreme temperatures. Cold waves from the Canadian north are common during the winter, with the lack of natural barriers to the polar winds in the form of high mountain ranges. Many towns accumulate snow in moderate amounts during the winter and days are rarely above freezing in the majority of Iowa. Winter is an off-season due to the lack of mountain slopes and the soft nature of the snow, which is not useful for exciting adventure activities.
Iowa is vulnerable to thunderstorms, tornadoes, and floods in late spring and the majority of the summer. Summer is subject to hail and damaging winds during the storms that destroy the crops. Roughly 50 thunderstorms and 47 tornadoes average in Iowa every year, mostly during the spring and summer. Heavy rainfall and the rapid thawing of snow during the summer cause severe flooding that results in large-scale destruction and stalls day-to-day life. Winter storms are common but rarely deposit large amounts of snow. More than the storms, the severe cold is a serious threat during the winter.
Weather in January
January is the coldest month of the year in Iowa, with temperatures in the frigid zone. The average temperatures in the western part of the state are between 5°F (-15°C) to 34°F (1.1°C); central is between 7°F (-13.9°C) to 32°F (0°C), while the eastern is in the 5°F (-15°C) to 34°F (1.1°C) range. January is the snowiest month of the year with a statewide average of 8" (203.2mm) to 10" (254mm) - Mason City in central Iowa is one of the highest accumulators of snow at 10.8" (274.3mm). Humidity is 70% in most regions, and the skies are cloudy many times. Reduced sunshine limits daylight to a few hours and the sun may even hide for days. Iowa has few spots for skiing during the winter due to the lack of thick snow and mountain slopes. Consequently, January is a discount season, as it does not attract many visitors to the state - instead, the cold drives the snowbirds from Iowa towards the south in search of warm winters.
Weather in February
February lies in the cold winter month of Iowa with the average temperatures in the cold 9°F (-12.8°C) to 39°F (3.9°C) zone across different regions of the state. Des Moines, the capital that lies in the central part of the state, averages a cold 19°F (-7.2°C) to 36°F (2.2°C). Sioux City in the west along interstate 29 averages 15°F (-9.4°C) to 35°F (1.7°C), while Cedar Rapids in the east along the interstate 380 sees day temperatures above freezing with the average in the 18°F (-7.8°C) to 36°F (2.2°C) range. February snowfall is in the range of 6" (152.4mm) to 8" (203.2mm) and a few days register over 40°F (4.4°C) as the curtain gradually lifts over the dreary cold. Snowstorms and blizzards occasionally occur during the winter but are not as severe as those in the Midwest and Northeast parts of the United States. Partly sunny days count up to 14 in February as the skies long for the return of the sun. Expect snow cover and icy roads in most places with weak sunlight and generally chilly weather.
Weather in March
March is a cold month that exhibits the first signs of the spring season in Iowa. Rain averages to the tune of 2" (50.8mm) statewide, while snowfall is in the range of 4" (101.6mm) to 5" (127mm). Spring weather is unpredictable that ranges from cold to sunny days, and there is always a possibility of a cold wave. March has approximately 15 sunny days, while the rest of the month is cloudy and wet. The average high temperatures are in the warm 41°F (5°C) to 51°F (10.6°C) range, while the nights are cold with average low temperatures in the cold zone of 21°F (-6.1°C) to 31°F (-0.6°C). Onawa in western Iowa averages between 23°F (-5°C) to 50°F (10°C), while Davenport in the east is between 28°F (-2.2°C) to 48°F (8.9°C). Though the day temperatures warm up on the arrival of spring, the nights are still cold, windy and soggy with a little bit of wetness in the air. Expect light snow in March and icy roads - pack in layers of warm clothing!
Weather in April
April is a wet month in Iowa with 3" (76.2mm) to 4" (101.6mm) of rain in the majority of the state. Snow is light and registers hardly 2" (50.8mm). The advance of spring brings warm temperatures to the delight of the tourist and locals alike. The average high temperatures are in the pleasant 58°F (14.4°C) to 65°F (18.3°C) range, while the average low temperatures rise above freezing and are in the 33°F (0.6°C) to 41°F (5°C) range. Sunlight improves vastly as the sun shines for nearly 7 hours a day. April in Iowa sees a rise in tourist numbers in the state parks due to the warm temperatures and the absence of extreme conditions. Spring brings greenery to the landscape of rolling hills, agriculture lands, and pastures, while the rain and melting of snow brings a fresh supply of water to the many rivers, lakes, and streams. The sun plays hide and seek with the clouds, as rain is unpredictable - so carry rain protection in the form of an umbrella or a raincoat.
Weather in May
May brings warm temperatures in spring along with cloudy and wet conditions. The average daily temperatures are in the beautiful 70°F (21.1°C) to 75°F (23.9°C) range, while the nights are comfortable between 48°F (8.9°C) to 55°F (12.8°C). Carroll in the west averages in the comfortable 49°F (9.4°C) to 72°F (22.2°C) range, while Mason City in the central part is between 47°F (8.3°C) to 70°F (21.1°C) and Burlington in the eastern ranges between a warm 53°F (11.7°C) to 74°F (23.3°C). By May, the last remnants of snow disappear from the ground. Rain is substantial and registers an average of 5" (127mm) in the state. May is the start of the severe season of thunderstorms and tornadoes, and it is an excellent idea to avoid a visit to Iowa during these severe bouts of weather. Almost 16 days are sunny in May, while the rest are cloudy and moist. The corn season gains ground amid the cacophony of singing birds, animals, and visitors. Beware of stormy weather, including heavy rain with occasional hail.
Weather in June
June begins the summer season in Iowa as the sun takes charge of the weather and drives away the remnants of the cold. The average high temperatures are in the warm 78°F (25.6°C) to 85°F (29.4°C) range, while average low temperatures hover around a mild 55°F (12.8°C) to 62°F (16.7°C). Sunny days are back with extended daylight that goes beyond 12 hours. June is wet in Iowa as the rain gauge accumulates an average of 5" (127mm) to 6" (152.4mm). Cloudy conditions are common as summer is prone to thunderstorms. Hailstorms are regular, along with heavy rain and destroy crops in many parts of the state. Keep an eye on the weather and be cautious during thunderstorms as open fields, agricultural areas, and pastures are more susceptible to lightning strikes. Humidity is often 70% inducing sweating, and while sweatshirts are useful, do not ignore the rain and carry adequate rain protection. June sees a rise in tourist numbers in Iowa despite rain and storm.
Weather in July
July is usually the hottest month of the year in Iowa as the sun regularly appears in the skies. The average high temperatures in the state are between 82°F (27.8°C) to 87°F (30.6°C), and the average low temperatures are in 60°F (15.6°C) and 67°F (19.4°C) range. Day temperatures often touch 90°F (32.2°C) to 95°F (35°C), and it is common for a few places to touch even 100°F (37.8°C). Davenport in the east averages between 63°F (17.2°C) to 84°F (28.9°C), while Shenandoah in the west is between 66°F (18.9°C) to 87°F (30.6°C). July experiences rain in the 4" (101.6mm) to 5" (127mm) range and is prone to stormy weather. The conditions are often hot and muggy, but people enjoy activities like fishing in the creeks, lakes, and rivers. Swimming and boating carry immense interest, but it is a better idea to spend midday hours in cool shade or indoor activities. Beware! Iowa is prone to severe flooding during the summer in many parts of the state, and the slightly flat topography does not help in quick receding of the waters.
Weather in August
August is a hot and humid month in Iowa as the majority of the state registers temperatures in the 65°F (18.3°C) to 85°F (29.4°C) average range. The sun appears on the horizon at least for 22 days in August, while the rest of the month has cloudy skies with wet conditions. Humidity adds to the heat woes, as the temperatures seem to be higher than the actual readings. Summer rainfall is moderate to heavy at times and records 4" (101.6mm) to 5" (127mm) statewide. In addition to thunderstorms, August is also vulnerable to tornadoes of varying intensities that strike Iowa in significant numbers during the summer. August is an excellent time to explore the Maquoketa Caves State Park, fish in the Okoboji Lakes, or go biking on one of the many beautiful trails in Iowa! There is plenty of wildlife in zoos and state parks in Iowa, and the tourist numbers rebound in August as the summer vacation attracts families to the state.
Weather in September
September is one of the best times to visit Iowa as it opens the doors to the beautiful autumn season with pleasant conditions. The summer rains recede to an average of 3" (76.2mm) to 4" (101.6mm) by early fall, and stormy weather decreases with them. The sun is present in the sky for at least 21 days, and the sunshine lasts for daily 6 to 7 hours. Humidity drops a little compared to that during the summer though cloud cover is present from time to time. The average high temperatures are in the 72°F (22.2°C) to 79°F (26.1°C) range, while the nights are comfortable in the average 47°F (8.3°C) to 56°F (13.3°C) zone. The oaks, maples, walnuts, and elms start to turn colors by Mid September as the beautiful fall season spreads over Iowa. North Iowa attains peak fall colors earlier than the central and southern parts. By the end of September, the landscape and scenery attain beautiful shades of colors, and the Driftless Area Scenic Byway is one of the best places to view the fall foliage!
Weather in October
October is temperate in Iowa and displays the peak fall foliage in the entire state. It is an excellent time to visit Iowa with pleasant temperatures and scenic landscapes. The average high temperatures are in the range of 60°F (15.6°C) to 67°F (19.4°C), while average low temperatures register 38°F (3.3°C) to 50°F (10°C) across the state. Rain is in the range of 2" (50.8mm) to 3" (76.2mm), while the conditions may be a bit frosty awaiting the first signs of snow. There is plenty of daylight and moderate humidity, but it is not odd to experience cold temperatures, especially at night. Waterloo in the east averages between 39°F (3.9°C) to 62°F (16.7°C), while Storm Lake in the west is between 39°F (3.9°C) to 61°F (16.1°C). Ames in central Iowa registers 41°F (5°C) to 64°F (17.8°C). Peak fall foliage colors display throughout Iowa by the fourth week of October - it is the last period of temperate weather, after which the state starts to become gradually colder.
Weather in November
November signals the end of the autumn in Iowa as the temperatures drop substantially. Sunshine reduces to 4 to 5 hours, and the days become short. Cloudy skies are regular as the night temperatures plummet drastically. The average daily temperatures are mild 45°F (7.2°C) to 55°F (12.8°C), while the nights are colder - between 27°F (-2.8°C) and 35°F (1.7°C). The first snowflakes of the winter drop by November, and it is common to experience 2" (50.8mm) to 3" (76.2mm) of snow. Fort Dodge in central Iowa registers 25°F (-3.9°C) to 45°F (7.2°C), Iowa City in the east is between 31°F (-0.6°C) to 50°F (10°C), while Lake Park in the west averages 25°F (-3.9°C) to 44°F (6.7°C). The trees shed leaves by late fall, and the roads become icy, and the conditions are frosty. The majority of the tourist population leaves Iowa by the start of November as the weather becomes cold, and the snow is unsuitable for skiing due to lack of high mountain slopes. Expect cold to increase further and dress in warm winter clothes!
Weather in December
December is brutally cold in Iowa with the average high temperatures in the 28°F (-2.2°C) to 37°F (2.8°C) range and the average low temperatures in the freezing 9°F (-12.8°C) to 21°F (-6.1°C) range. Temperature variations between different parts of the state are unsubstantial, and the days and nights do not see extreme deviations. Milford in western Iowa averages between 9°F (-12.8°C) to 28°F (-2.2°C), while Cresco in eastern Iowa is between 10°F (-12.2°C) to 27°F (-2.8°C). Snowfall is moderate in December and averages 8" (203.2mm) to 10" (254mm) statewide with 1" (25.4mm) to 2" (50.8mm) of rain. Winds often blow at high speeds to enhance the coldness of winter. December has roughly 14 short days with 4 to 5 hours of sunlight, while the remaining days are cloudy with the sun present for short periods. Christmas and New Year are not usually white in Iowa as the snow is moderate at best, but the severe cold needs warm winter coats, gloves, boots, and caps! Overall, the conditions are unfavorable to visit Iowa during the winter.