California has a diverse climate ranging from a wet temperate rainforest in the north, hot, arid desert in the interior, snowy alpine in the mountains and the warm Mediterranean in the rest of the state. The Pacific Ocean borders the western part of the state, Oregon the north, Arizona and Nevada the east, and Mexico the south. The state's varied topography covers the Pacific Ocean on the west coast to the Sierra Nevada mountain range in the east, and redwood forests in the north to the Mojave Desert in the south.
The climate ranges from polar to subtropical due to the large size of the state. Summer fog is regular on the coast due to the cold California current while inland areas experience cold winters and hot summers. Proximity to the Pacific Ocean regulates summer temperatures of parts of Los Angeles and San Francisco near to the coast and creates different microclimates as downtowns of these cities experience hotter summer temperatures and colder winters.
Northern parts of California are rainier than the south, and the high mountain ranges influence the climate as western mountain slopes receive more rain than the eastern leeward parts that lie in the rain shadow region. The high mountains on the western side have an alpine climate while those in the east have hot summers and cold winters. Death Valley, a desert on the eastern side, is the hottest location in the world with a recorded temperature of 134°F (56.7°C) while Boca has the lowest recorded temperature in the state of -45°F (-42.8°C).
Summers tend to be mild along the coast such as the San Francisco area with an average high temperature of 67°F (19.4°C) at the peak in August while the central and eastern parts of California tend to be hot with average high temperatures of 91°F (32.8°C) to 97°F (36.1°C) in Sacramento and Fresno. Winter average low temperatures are around 40°F (4.4°C) to 50°F (10°C) in the coastal areas while Mammoth Lakes in the mountains of Sierra Nevada freezes to an average low temperature of 15°F (-9.4°C). Spring is damp and warmer than the winter while autumn is cooler than the summer in most parts of the state.
Rainfall is chiefly in the winter in most parts of the state, and the annual precipitation in California is around 18" (457.2mm). Snowfall is common in the northern alpine regions where it averages in the range of 60" (1524mm) to 70" (1778mm) over the year. Summer fog is a distinct feature of the western coasts while frost is regular during winter in various parts of the state.
The best time to visit California
The best time to visit many parts of California is during spring and autumn, while some are fine even in the peak of summer. Mid-spring is a good time as the winter cold recedes and the sun resumes duties in full glory. Western coastal regions like San Francisco experience mild and pleasant summer days in the 50°F (10°C) to 70°F (21.1°C) range. Up in the north, summers are comfortable without extremities of temperatures. Autumn has mild temperatures, particularly in the central, eastern and southern parts of the state with a sprinkling of rain. Generally, both spring and autumn tend to be less hot and humid than the summer in a majority of areas of California and are more pleasant.
The worst time to visit California
Winter from December to February is the worst time to visit most of California as the state experiences cold and chilly weather. Northern California with its highlands and mountain ranges is chilly as the higher altitudes accumulate large amounts of snow often up to 100" (2540mm). On the western side, the coastal areas around the Pacific Ocean are relatively warmer compared to the inland regions, but temperatures are low during the winter nights. The deserts in the south also tend to be cold during the winter nights. Although there are a few areas in the state where summers are avoidable, usually winter is the most avoidable period in the majority of California.
California lies in the Pacific Ring of Fire, which makes it susceptible to earthquakes, tsunamis, and volcanic activity. Many fault lines run through the state such as the San Andreas Fault and the Hayward Fault that cause earthquakes of variable intensity; as many as 37000 earthquakes occur in the state, but many are too weak to take notice. Wildfires are a threat in the dry summers that consume hundreds of acres of forestlands. Winds such as the Santa Ana add to the intensity of the hazardous climatic events. Floods, landslides on steep terrain and droughts occur in various parts of the state due to the diversity of weather patterns.
Weather in January
January is the coldest month of the year in California with the mountains of the Sierra Nevada in the frigid 3°F (-16.1°C) to 15°F (-9.4°C) average range amid snowy alpine conditions. The state has the most extensive variety of pine trees in the world that makes spectacular scenery in the backdrop of the snow! Elsewhere in the state, however, the cold is more manageable with day temperatures of 54°F (12.2°C) to 70°F (21.1°C) and nights in the range of 30°F (-1.1°C) to 45°F (7.2°C). Sacramento in the central part of the state experiences cold weather with average temperatures in the 39°F (3.9°C) to 54°F (12.2°C) while San Diego in the south is mild between 49°F (9.4°C) to 65°F (18.3°C). Rainfall occurs almost everywhere in the state in January to the tune of an average 3" (76.2mm). Expect the sunshine to last only for about 6 hours a day with plenty of cloud cover and damp conditions during January. Although New Year draws crowds to California, it is worth to wait for the upcoming pleasant weather of spring.
Weather in February
February is the last winter month in California, which sees average low temperatures in the cold 38°F (3.3°C) to 48°F (8.9°C) zone and the average high temperatures in the 58°F (14.4°C) to 68°F (20°C) range across different areas of the state. Los Angeles, down south, is much warmer and pleasant with average low temperatures of 50°F (10°C). The winter sun rays are milder compared to the summer as the sunshine lasts for an average of 7 hours in the middle of the clouds with plenty of humidity and wetness in the air. The eastern part of the state in the rain shadow region of the mountains that borders Nevada gets much less rain to the tune of 1.5" (38.1mm) and experiences semi-arid desert conditions. Overall, expect frost and mild wintery conditions with flakes of snow in the face of cold fronts. However, extremely low temperatures are uncommon in most parts of the state, and warm winter clothing usually suffices for the mildly cold days.
Weather in March
March sees the arrival of the beautiful spring with a fresh aroma of the blossoming of wildflowers, especially in the northern highlands and the rural hinterlands. It is wet with a fair amount of rain, a touch of humidity and the sunshine peeking through the clouds intermittently — the average temperatures in the state range from a low of 45°F (7.2°C) to 50°F (10°C) to a high of 65°F (18.3°C) to 70°F (21.1°C). San Jose along the western coast registers mild temperatures in the 47°F (8.3°C) to 66°F (18.9°C) range while Pasadena in the southern inland is a little warmer in the 50°F (10°C) to 72°F (22.2°C) range. Rain is moderate and ranges between 1" (25.4mm) to 3" (76.2mm) in most parts of the state. Though March is damp with mild day temperatures and cold nights there is no shortage of sunny days in the state - it is better to pack in layers and carry an umbrella or a raincoat as a useful accessory especially in the northern highlands.
Weather in April
April is a beautiful month in California, which spreads the wings of spring across the entire state. The wildflowers, redwood and pine trees, and giant sequoia trees provide a natural beauty to the landscape as the lands, forests, and hills come alive after the departure of the cold and wet winter. April is one of the best times to visit California with the average temperatures in the 50°F (10°C) to 70°F (21.1°C) range across the state. Rain limits to less than 1" (25.4mm) in many parts of the state and it is the end of the snow season. Sunshine abounds everywhere as spring weather rolls along its merry ways. Redding in the northern interior part of the state sees average temperatures in the 45°F (7.2°C) to 70°F (21.1°C) range. April sees early tourists due to the pleasant sunny weather with a rise in temperatures and the absence of wet conditions. Expect the sunny conditions to improve with the progress of the month, but the sea temperatures are still a bit on the cooler side for swimming.
Weather in May
May witnesses brilliant sunshine in California that lasts up to an average of 8 hours a day. Temperatures at many places are between a warm 75°F (23.9°C) to 80°F (26.7°C) during the day while the nights are temperate between 50°F (10°C) to 60°F (15.6°C). Beaches in the south such as Long Beach and Huntington Beach have reasonably warm waters with the sea temperature around the 70°F (21.1°C) that many visitors find refreshing and enjoyable. The sunrays are not of the same intensity as those in the summer, which makes May visits to California quite pleasant in the absence of the swarming summer crowds. Rain almost disappears from the majority of the state with the progress of the spring season and humidity decreases with a subsequent decrease in cloud cover. Overall, spring is lovely, and light clothing adds further delight while exploring the various attractions of the state.
Weather in June
June is summer in California with average high temperatures in the sunny 75°F (23.9°C) to 85°F (29.4°C) range and average lows of 55°F (12.8°C) to 65°F (18.3°C). An average of 9 hours of daily sunshine registers in the month as the days are mostly sunny and bright. El Centro near to the Mexican border in the south records an average high temperature of 103°F (39.4°C). On the eastern side, the proximity of the Mojave Desert sees day temperatures cross the 100°F (37.8°C) mark frequently. On the other side, coastal areas such as Oceanside see much milder summers with the average high temperature around 152.6°F (67°C) in June. The near absence of rain provides further reason for tourists to flock to the state and its beaches along with the desire to witness the peculiar morning summer fog. June is an excellent month with moderate temperatures in many areas and sees a significant rise in tourist numbers in California.
Weather in July
July is peak summer in California with average high temperatures around 80°F (26.7°C) to 85°F (29.4°C). The northern parts and highlands, coastal areas and central parts are a little cooler compared to the eastern and southern parts that border the states of Nevada and Arizona, which have a semi-arid climate. The desert areas regularly cross 110°F (43.3°C) during the days while the nights see a difference of 30°F (-1.1°C) in temperature. It is an excellent time to hike the mountains whose high altitude passes are impassable in the winter due to snow. Rain and humidity drop substantially in the summer and makes way for mostly clear skies. Summer sees peak crowds in the Yosemite National Park area - be sure to get weather updates regarding wildfires and flash floods! Take precautions against the ultraviolet rays of the sun, particularly around the beaches where people prefer light clothing. Overall, California summers are mostly temperate compared to those of the neighboring states of Nevada and Arizona.
Weather in August
August is a hot and dry summer month with many parts of the state in the 85°F (29.4°C) to 90°F (32.2°C) range during the day. The skies are dry and mostly clear with relatively lesser humidity compared to the winter. Nights are around the 60°F (15.6°C) to 65°F (18.3°C) in many areas except the deserts and mountains where the temperatures see more deviation than the plains and lowlands. Many sunny days adorn August with sunlight around an average of 9 hours, which sees a rush of visitors to California's beaches, mountains, and national parks. The San Francisco Bay Area sees warm days and nights in the average range of 55°F (12.8°C) to 68°F (20°C) with great ocean waters at mild temperatures of 65°F (18.3°C). August signals the end of the summer and the temperatures start to drop gradually by the end of the month, which makes light sweatshirts a suitable outfit during the days and nights in the core regions of the state.
Weather in September
September beckons the beautiful autumn season to California with its majestic colors, splendor and pleasant weather conditions. High temperatures touch 90°F (32.2°C) for a few days in some places, but usually, they are between 75°F (23.9°C) and 85°F (29.4°C). Nights become cooler with a little rise in humidity compared to the summer and intermittent cloudy and sunny skies. The summer fog-shrouded regions of the northern coastal regions of the state see some of the sunniest days in the early autumn. Perfect blue skies do occasionally occur at many places while some places like Hollywood witness spectacular blue skies for most of the year. Fall sees perfect weather in the Yosemite area between the 47°F (8.3°C) to 83°F (28.3°C) range with warm days and temperate nights. Though a shade lesser than the northeast of the United States, fall colors are a beautiful sight with an abundant variety of trees and flowers in California across diverse terrain, especially the High Sierra.
Weather in October
October is another great time to visit California with the autumn in full cry and some of the best weather conditions in the state. Average temperatures across the state are in a temperate zone of 50°F (10°C) to 80°F (26.7°C) with many sunny days in the month and the relatively meager amount of rain. Humidity is around 65% with mostly clear skies and mild nights. Even the southern hinterlands like Bakersfield, Burbank, Lancaster, and Victorville, are around a perfect range of 46°F (7.8°C) to 78°F (25.6°C). By the end of October, the first signs of rain and snow announce themselves in the mountain ranges at high altitudes. The summer crowds dwindle by late fall, and it makes a great time to visit California along with the pleasant weather conditions. The beaches mostly see the local population as the temperate seawaters attract swimmers and surfers alike - it is a wonderful time to be in California during October!
Weather in November
November ends the beautiful autumn in California, and the winter sets its sights on the state by the end of the month. The average temperatures are in the mild 45°F (7.2°C) to 65°F (18.3°C) with a little decrease in the number of sunny days. Sunlight drops to an average of 7 hours, and there is a rise in humidity levels. Rain often follows the heavy clouds, and the state sees an average of 2" (50.8mm) to 3" (76.2mm) in many parts; Redding in northern California is one of the wettest places in November with about 4.5" (114.3mm) of rain. Temperatures are cozy in most parts of the state, and overall the weather is agreeable with a mild degree of coldness in the air, especially by the end of November. Expect rains anytime and carry protection for the rain - an umbrella or a raincoat. The onset of winter sees a drop in tourist numbers who prefer to wait for weather that is more favorable.
Weather in December
December lies in the cold of winter with the average high temperatures in the 55°F (12.8°C) to 60°F (15.6°C) range and the average low temperatures in the mildly cold 37°F (2.8°C) to 45°F (7.2°C) range across the northern parts of the state. Southern parts of California are a little warmer than the north with the average highs around 60°F (15.6°C) to 68°F (20°C) and the average lows around 45°F (7.2°C) to 55°F (12.8°C). December is rainy with an average of 3" (76.2mm) of rain; San Rafael in the north is one of the wettest places in the state with 7.6" (193mm) of rain. Snow falls in large amounts in the mountains of Sierra Nevada while it is meager along the coast and lowlands. Sunshine is usually up to 6 hours due to an increase in cloud cover and humidity that goes above 78%. The winter is cold, but temperatures do not drop below freezing in most parts of the state. The period after Thanksgiving Day usually does not see many visitors to California due to the damp and cold conditions. [Resources]
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