USA: Weather Overview
The USA, due to its immense size and geographical diversity, has various climates in different locations. The south and west regions tend to be warmer and dryer while the north and east are more temperate with colder winters. Coastal regions are naturally milder than inland areas away from large bodies of water. Mountainous regions of higher altitude are colder and receive higher levels of precipitation. The USA can be broken up into different climatic regions that stretch in bands across the country, but to make this more digestible to the holiday-maker this guide will stick to the following geographical regions.
The Pacific Northwest coast of the USA is the wettest part of the country receiving year-round drizzle, some storms and fog in the summer. However, summers are usually mild to hot and drier than the winters which are mild to cold. The Pacific southwest coast, California, receives pleasant weather all year with long, hot summers and mild winters. The interior western states are drier, partially desert, with greater extremes of temperature.
Washington and Oregon
Washington and Oregon are coastal states, split by the Cascade Mountains. Western areas receive a temperate, marine climate while east of the mountains the climate is dry. Seattle in Washington and Portland in Oregon see quite dry summers with the occasional thunderstorm and average high temperatures around the mid-20s in the height of summer. Summertime on the coast is often plagued with a dense fog but when this clears hours of sunshine are to be enjoyed. Spring and autumn see average day time temperatures around 12 °C. The winter sees average highs around 8°C and lows around 2°C. Snow does not fall often in urban areas but has been known in December. Precipitation is high from autumn to spring and sees the ski season starting in November. East of the Cascade Mountains conditions is semi-arid. The Columbian River Plateau is the driest area with a number of deserts.
Officially nicknamed the Golden State due to the discovery of gold in 1968, arguments have been made for California to steal Florida's nickname, the Sunshine State. California is famed for the hot weather of its south coast but the state experiences hugely varied weather as it stretches from the north to the south of America and has diverse topological features.
San Francisco, on the northern part of the coast, receives fairly mild summers with high temperatures averaging around 20°C in July and August. Night times cool off to around 13°C. The mild winters are only around 7°C cooler than the summers. This still has a high impact on tourism and most visitors stick to the summer months, but the variation between the highs and lows of the year are relatively tiny. The northern parts of California are generally much wetter than the south. Los Angeles on the southern coast is hot all year round with a sub-tropical climate. It has a dry season from May till October with average highs between 20 and 30°C, the peak being in August. The wet season from November to April is cooler with average highs staying in the early 20s. Los Angeles sees an average of 263 days of sunshine a year. To the east of California's mountains lie its arid desert regions. Coastal California is not susceptible to tropical cyclones. Earthquakes are quite common around the San Andreas Fault which runs right through the state.
Idaho receives a temperate climate with all four seasons remaining distinct. Summers are very hot, seeing average highs around 30°C while winters are devastatingly cold, sometimes dropping below 0°F, which is a -18°C. The record low is an unthinkable -51°C. The protection of mountains gives Boise and Lewiston longer summers than the rest of the state.
Utah and Nevada
Two of the four desert states, Utah and Nevada are far from their primary water source, the Pacific Ocean, and protected by the Sierra Nevada, the Cascades and the Rocky Mountains; they receive low levels of precipitation. The regional climate depends largely on altitude, with lower altitudes seeing typical desert conditions and higher elevations receiving more temperate climates. The desert terrain and lack of water result in vast temperature differences from day to night. Salt Lake City, in Utah, receives all four seasons with the hot summers tempered by winds from the lake, and cold, snowy winters with temperatures regularly dropping below 0°C. Las Vegas sits right in the middle of the Mojave Desert in Nevada. It receives almost 300 days of the sunshine year and minimal rainfall that falls in short storms, sometimes causing flash floods. The height of the summer sees blistering daily averages in the 40s with stifling nights in the 20s. Winters are short and mild with day time temperatures bottoming in January at 15°C, and night times dipping just below freezing. Mountainous areas are much cooler. The Rockies receive a lot of snow and are famous for skiing.
The southwest is typically hot and dry with more temperate climates to the northeast. Tornado Alley stretches between the Rocky and Appalachian Mountains in the east of this region and tornados cause havoc through spring and early summer.
Arizona and New Mexico
The remaining two desert states, Arizona and New Mexico, see much the same climate as Utah and Nevada: hot and dry. As stated above, regional climate depends largely on altitude, with lower altitudes seeing typical desert conditions and higher elevations receiving more temperate climates. From May till October is the monsoon season during which flash-flooding is possible. The most famous geographical feature of the area and one of the seven wonders of the natural world is the Grand Canyon. Cutting across central and northern Arizona, the Grand Canyon is a great example of the extreme contrasts between climates at different altitudes. Its south rim is 1000 feet higher than its north rim and sees snowy winters and warm summers around 20°C with cool nights while the north rim sees ice and snow all year round. The inner canyon, deep below the rim, sees summer highs nearing the 40s and night times do not cool off so drastically.
The Grand Canyon, USA.
Texas's great size means it straddles a number of climatic regions, but it is generally hot and dry in the summer and mild to cold in the winter. The Texas High Plains on the New Mexican border are semi-arid and desert-like. The mountains on the Mexican border see much cooler weather but lower south arid conditions return. The rest of Texas is mostly sub-tropical, getting milder towards the coast. In Austin summer highs average around 36°C while winter sees misleading highs around 16°C; it can often be much colder. Houston is similar though slightly milder with average summer highs around 34°C and winter highs around 17°C. Rainfall is always low. Coastal Texas is prone to hurricanes and the north contains the end of Tornado Alley. Tornados usually occur in spring and early summer.
Oklahoma is a temperate state receiving a continental climate. It receives long, hot, dry summers and cold, snowy winters. The east of the state is influenced by the humid, sub-tropical climate blown up from the Gulf of Mexico. To the west, conditions become increasingly arider. Oklahoma City, sitting in gentle prairie land, is one of the sunniest and windiest cities in the USA. Most of Oklahoma is part of Tornado Alley and the state is visited by numerous tornados, mostly between April and June.
The central states have a temperate continental climate with four distinct seasons.
Montana, Wyoming and Colorado
Colorado Mountains, USA.
Although Montana is considered part of the Great Plains, it has many mountains. The Rockies, and the continental divide stretch through western Montana, right through Wyoming and Colorado. The mountains restrict the flow of cool air from the east to the west and warm air from west to east. The Rockies have unpredictable weather from day to day through the four seasons are very distinct. Summers are warm and dry, interrupted by thunderstorms. Snow starts falling in the autumn and sees the start of a long ski season through the best of the ski season is seen to be in spring. Winter sports enthusiasts come from all over the world to ski in Colorado's famed resorts such as Vale and Beaver Creek. The winter sees deep snow and regular blizzards with temperatures falling at night to around a bitter -37°C. Spring is very changeable with wet weather and increasing temperatures seeing the snow gradually melt away. East of the mountains weather is warmer with summers getting hotter the further south across the three states. It is usually quite dry. Winters are extremely cold.
North Dakota and South Dakota
The Dakotas receive a temperate climate with four distinct seasons. Summers are hot and dry with periods of drought. The winters are bitingly cold.
Kansas and Nebraska
Both states receive continental climates with distinct seasons. Summers are hot and winters are cold. The western regions are dry and windy. The east is much more humid and receives the majority of the states' rain. This falls mostly in spring and summer and which is when Kansas, famously part of Tornado Alley, sees the majority of its tornados. Summer in Kansas City is sweltering, seeing average highs in the mid-30s with humidity at uncomfortable levels. The sun stays out for around eleven hours a day and the nights provide little respite from the heat. Spring and autumn see dramatic changes in temperature, quickly heating up from 12°C in April to 18°C in May, and dropping from 20°C in October to 12°C in November. Night times are considerably cooler. Winter months are very cold with day times lingering between 1°C and 6°C, and night times falling well below zero.
The Midwest is known for being hot and humid though it does receive all four seasons.
Minnesota, Iowa and Wisconsin
These states have typical humid continental climates, enduring extremes of temperatures in the summer and winter months. Lakes Michigan and Superior in Wisconsin have some moderating effects on the surrounding areas. The Mississippi River starts in Minnesota from Lake Itasca and stretches all the way across the USA to the Gulf of Mexico. It often creates state borders as it does in the case of these three states. The Mississippi and the lakes in the surrounding areas are a real draw for water sports lovers. Waterskiing was invented on the stretch of the Mississippi between Minnesota and Wisconsin known as Lake Pepin. The whole area is prone to heavy precipitation seeing lots of snow in the winter and heavy rain in the spring and summer. Thunderstorms are a regular occurrence, tornadoes are not rare and the Mississippi is susceptible to flooding. However, summer months still see a lot of sunshine and the hot temperatures and beautiful waters draw many visitors.
Michigan also has a humid continental climate for the most part, but the Upper Peninsula and the northern part of the Lower Peninsula receive much colder weather. They see warm, short summers and long, upsettingly cold winters. January and February often see average highs below freezing. The state is prone to violent thunderstorms and tornadoes which are more frequent in the southern region.
Missouri, Illinois, Indiana and Ohio
These states also have humid continental climates apart from their most southerly regions where the climate is humid sub-tropical. While the majority of these states receive the typical blazing hot, humid summers and snowy, cold winters, the southern parts receive milder winters. Thunderstorms are common in all states; Indiana sees some tornado activity and earthquakes are not unheard of in Ohio. The Missouri River is prone to heavy flooding. July and August in Chicago in Illinois are beautifully hot months, seeing an average high around 28°C. January, the coldest month, sees average lows of -8°C with regular snow.
The southern states are typically hot in the summer with mild winters. The whole area is prone to thunderstorms and coastal regions are sometimes hit by hurricanes.
Arkansas, Kentucky, Tennessee, West Virginia, Virginia and North Carolina
These states enjoy a humid sub-tropical climate receiving all four seasons with hot summers and mild winters. There are many regional variations, mainly due to the Blue Ridge section of the Appalachian Mountains which stretch across all of these states apart from Kentucky. In these areas higher elevation correlates with cooler temperatures and increased snowfall in winter months. West Virginia, which is very mountainous, is one of the wettest and cloudiest states in the USA. North Carolina is actually the wettest of the eastern states due to the rain-bearing southerly winds that come over the mountains. However, in all of these states where rainfall is highest through spring and summer, sunshine regularly follows the heavy downpours. Kentucky and Tennessee are far enough west, away from the ocean, to be safe from hurricanes, but tornados are a risk. Virginia and North Carolina's Atlantic coast means they are susceptible to hurricanes that often do damage far inland.
Virginia Beach, on Virginia's coast right on the border with North Carolina, sees average highs reaching just into the 30s in July and August. Wintertime sees averages staying above freezing though it can dip below and while snow is rare, it has been known to happen. This city is spared the majority of hurricanes as their usual path is to the north.
Nashville Tennessee, USA.
Louisiana, Mississippi, Alabama, Georgia and South Carolina
The states of the Deep South also have a pleasant humid sub-tropical climate with the southern parts of the states, and all of Louisiana, with coasts on the Gulf of Mexico, experiencing higher temperatures year round. Northern regions are especially cooler in the Appalachian Mountains which reach into Alabama, Georgia and South Carolina. Thunderstorms are common and there is the risk of hurricanes in the summer and autumn months. Spring and autumn are warm with day time temperatures sometimes reaching up into the 20s. Summers are long and hot, seeing daily average highs in the mid-30s. Winters can get down to freezing but snow is rare, apart from in the mountains. Rainfall is quite high all year round with the majority falling in the summer months in thunderstorms. New Orleans, on the coast of Louisiana, has been identified as one of the three cities in America most susceptible to hurricanes.
Most of Florida also has a humid sub-tropical climate, usually warmer than the states to its immediate north. But closer to Lake Okeechobee the weather quickly increases in heat and south of Lake Okeechobee Florida experiences a true tropical climate.
Key West, Florida USA.
Jacksonville in the north of Florida shares its summer temperatures with Miami in the south, seeing summer average highs around 33°C. However, Jacksonville is much colder in the autumn, spring and winter, seeing average lows of 6°C in January.
Miami 's tropical climate means warm to hot temperatures year round. It has hot, humid summers with the monsoon season falling between May and October, and warm, dry winter. January, the coolest month, sees average highs of 24°C and average lows of 16°C. Miami is statistically the most like city in America to be hit by a hurricane.
The north-eastern states are known for their pleasantly hot summers and snowy winters.
Maryland and Delaware
These states lie in the transition zone between a humid sub-tropical climate and a continental climate and as such have regional variations in weather. The southern regions of both states receive humid sub-tropical conditions. While the whole region enjoys long, hot summers, the northern areas see longer and colder winters. The east of Maryland and most of Delaware are part of the flat Atlantic Coastal plain. In the northern regions of Maryland, the flat land meets the Appalachian Mountains which see heavy snow and temperatures below -12°C every winter. The states are surrounded by water: the Chesapeake Bay in the west, Delaware Bay in the east and the Atlantic Ocean to the northeast. The states' climates are moderated somewhat by the abundance of water and coastal winds. Hurricanes are possible through North Carolina, to the south, provides protection from the majority of these tropical cyclones. The District of Columbia, Washington D.C., is surrounded by Maryland apart from its southwest border which is with Virginia. It falls in the area's humid sub-tropical climate. Scorching summers see 30°C average highs in July and August.