The United States spans nearly every major climate type on Earth, from tropical rainforests in Hawaii to arctic tundra in Alaska, with vast deserts, humid subtropics, and temperate coastlines in between. That range exists because the country covers roughly 25 degrees of latitude, sits between two oceans, and includes mountain chains that dramatically alter weather patterns from one valley to the next. Understanding U.S. climate means looking at distinct regional zones, their rainfall and temperature profiles, and how those patterns are shifting.
Major Climate Zones Across the Country
Climate scientists use the Köppen classification system to sort regions by temperature and precipitation. The contiguous U.S. alone contains at least a dozen of these categories, and adding Alaska, Hawaii, and the territories pushes the count even higher.
The Southeast, from eastern Texas through the Carolinas, falls into the humid subtropical zone. Summers are hot (warmest months averaging above 72°F), winters are mild, and rain falls year-round, though amounts vary month to month. This is the climate most Americans experience, since it covers the most populated stretch of the eastern half of the country.
The Pacific Northwest coast, from northern California through Washington, has a marine west coast climate. Temperatures stay moderate all year, rarely getting extremely hot or bitterly cold, with steady rainfall spread across the seasons. Average monthly temperatures stay below 72°F even in summer, giving the region its famously mild, overcast character.
Much of central and Southern California has a Mediterranean climate, defined by dry, hot summers and mild, wet winters. The wettest winter months receive at least three times as much rain as the driest summer month, which is why wildfire season and the rainy season are so starkly separated there.
The Great Basin and interior Southwest are classified as mid-latitude desert or subtropical desert, where evaporation far exceeds rainfall. Nevada averages just 9.5 inches of precipitation per year. Utah receives about 12 inches, and New Mexico around 14.6 inches. Winter freezing is common in the higher-elevation deserts of Nevada and Utah, while lower deserts in Arizona rarely see frost.
The Great Plains fall into mid-latitude steppe territory: drier than the East but wetter than the true deserts to the west. This semi-arid belt supports grasslands rather than forests and experiences wide temperature swings between summer and winter.
The upper Midwest and interior Northeast have a humid continental climate with warm to hot summers and cold, snowy winters. Alaska’s interior is subarctic, with short growing seasons and winter lows that can plunge well below zero. Hawaii, by contrast, sits in the tropical zone, with warm temperatures year-round and lush rainfall on windward slopes.
Wettest and Driest Regions
Precipitation varies enormously. Louisiana is the wettest state in the lower 48, averaging about 60 inches of rain per year, with every month delivering between 4 and 6 inches. Mississippi is close behind at 59 inches, and Tennessee averages around 54 inches. The Gulf Coast and central Appalachian states receive the most consistent year-round moisture because warm, humid air flowing north from the Gulf of Mexico feeds frequent thunderstorms and frontal systems.
On the dry end, Nevada receives just 9.5 inches annually, with some months averaging barely half an inch. The driest pockets, like Death Valley in California, get under 2 inches a year. New Mexico’s rainfall is heavily concentrated in late summer, when monsoon thunderstorms in July and August deliver roughly twice as much moisture as any other month. That seasonal burst greens up the desert briefly before dry conditions return.
Severe Weather Hotspots
The U.S. experiences more tornadoes than any other country, and two areas stand out. “Tornado Alley” stretches from central Texas northward through Kansas, Nebraska, and into northern Iowa, then east to western Ohio. Tornadoes here peak in late spring, with occasional activity in early fall. A second hotspot, sometimes called “Dixie Alley” along the Gulf Coast, sees its tornado peak later in the year, from October through December.
Florida is the other major severe weather zone. Nearly daily thunderstorms during summer produce frequent tornadoes, and the state’s peninsula is regularly hit by tropical storms and hurricanes. The broader Gulf and Atlantic coasts face hurricane season from June through November, with peak activity in August and September.
The western U.S. deals with different hazards. Prolonged drought and low humidity create dangerous wildfire conditions, particularly in California, Oregon, and the interior mountain West. Winter storms can dump enormous snowfall in the Sierra Nevada and Rockies, sometimes producing avalanche risks and flooding during spring snowmelt.
How U.S. Temperatures Are Changing
The year 2024 was the warmest on record globally since tracking began in 1850, coming in at 2.32°F above the 20th-century average. The U.S. has tracked with that broader trend. When the USDA updated its Plant Hardiness Zone Map in 2023, using temperature data from 1991 to 2020, roughly half the country had shifted into the next warmer half-zone compared to the previous 2012 map. That shift represents warming in the range of 0 to 5°F for minimum winter temperatures across those areas.
This warming has practical consequences. Gardeners and farmers in much of the country can now grow species that would not have survived winters a few decades ago. Frost seasons are shorter, growing seasons are longer, and heat waves are more intense in regions like the Southwest and southern Great Plains. The warmth also feeds heavier rainfall events in the East, because warmer air holds more moisture.
Sea Level Rise Along U.S. Coasts
Coastal climates are being reshaped by rising seas, though the rate varies dramatically by region. NOAA projections estimate that by 2050, relative to year-2000 levels, the Gulf Coast will see the most rise at 0.55 to 0.65 meters (roughly 22 to 26 inches). The East Coast is close behind at 0.40 to 0.45 meters (16 to 18 inches). The West Coast, Hawaii, and the Caribbean face a more moderate 0.20 to 0.35 meters (8 to 14 inches). Southern Alaska is actually projected to see a relative decrease in sea level because the land itself is rebounding upward as glacial weight disappears.
For Gulf Coast cities like Houston, New Orleans, and Miami, those projections translate to more frequent tidal flooding, saltwater intrusion into freshwater supplies, and greater storm surge damage during hurricanes. East Coast cities from Norfolk to Boston face similar challenges, particularly during nor’easters that push water onshore for extended periods.
What Climate Feels Like Region by Region
If you are planning a move or a long visit, the day-to-day experience of climate matters more than classification labels. In the Southeast, expect sticky summers where heat index values regularly exceed 100°F, mild winters with occasional ice storms, and thunderstorms that pop up on summer afternoons with little warning. Spring and fall are the most comfortable seasons.
In the Desert Southwest, summer highs above 110°F are routine in low-elevation cities like Phoenix, but humidity is low, so shade and air conditioning make an enormous difference. Winters are mild and sunny, which is why the region attracts so many seasonal residents. The trade-off is water scarcity: everything from landscaping to municipal planning revolves around limited supply.
The Pacific Northwest is temperate but gray. Seattle’s annual rainfall total is actually lower than many East Coast cities, but it comes as persistent drizzle spread over many months, meaning overcast skies dominate from October through May. Summers are dry and mild, often spectacularly pleasant, with long daylight hours.
The Upper Midwest and Northern Plains have some of the widest temperature swings in the country. Parts of Minnesota and the Dakotas can see summer highs near 100°F and winter lows near negative 30°F, a spread of 130 degrees across the year. Snow can linger on the ground for months, and wind chill makes the cold feel far more extreme than thermometer readings suggest.
Alaska is its own world. Fairbanks, in the interior, has recorded temperatures ranging from negative 50°F in winter to over 90°F in summer. Coastal communities like Juneau are milder but extremely wet, receiving over 60 inches of precipitation a year. Hawaii stays warm year-round, with coastal temperatures typically between 75°F and 88°F, but microclimates vary sharply: the windward side of Maui’s mountains can receive over 300 inches of rain annually, while the leeward coast stays dry and sunny.