| Central Coast Weather |
| California is a region of contrasts. One expects to start in the temperate forests of the North Coast and transition to the very arid deserts of the Southeast corner of the state. You can even get used to the temperature gradient in the ninety miles from the City of Sacramento to the city of San Francisco. Sacramento can be over 100 degrees and at the same time “the City” (San Francisco) is foggy and in the low 60’s. But the central coast takes these differences to the extreme.
On a summer day, the Embarcadero in Morro Bay can be foggy and in the low 60’s while a mile away the sun is out and the temperature a mild 80 degrees. Climbing the coastal mountain range and entering the valley containing Paso Robles and Atascadero, 16 miles to our east and the temperature soars to the mid to high 90’s. Moving further east, another 30 miles, to the San Joaquin Valley will put the temperature well over 100 degrees. In fact, it is the temperature gradient between here and the San Joaquin Valley that causes the temperature gradient. The ocean current from Alaska flows right along the coast and so the water is very cold (about 50-55 degrees F.) Further from the shore the ocean is warmer and the air loaded with moisture. The prevailing winds are out of the west and so the air moves across the warm ocean water and over the cold coastal water, and, as it does the temperature drops and fog forms. Therefore, the coast is foggy. The high temperature of the central valley causes the air in the valley to become less dense and rise. The raising air mass creates a vacuum that sucks the cool air in off the ocean. As the air moves on shore and tries to climb over the coastal mountains it warms up again and the fog disappears. The result of this is that the coastal areas wake to foggy, still mornings. As the valley warms the air starts to move inland and by mid-morning the winds can blow pretty strong. The strong winds pull in the ocean air and keep things cool. This mechanism is very stable and well understood, but it is only true during the summer months. You do have to understand that summer in California lasts until sometime in October or even November. Then things change. As the temperatures of summer diminish into fall, the big valley gets cooler and the thermal winds quit, the coast clears and warms up. The early fall is the favorite time of the year for the permanent residence – the days are warm, the skies are clear, the wind is low and the tourists are gone. But there is no free lunch. This change in the weather has it own hazard – fire season. There is no rain in central and southern California from March until the end of October – none. The grasses, oak trees and pines get very dry, tinder dry. The summer winds off the ocean are moist and the fire danger is there and is a threat and we do get forest fires during the summer. But once the on-shore breezes stop, the vegetation gets even dryer. Then we get the Santa Ana winds. One of the permanent features of California’s summer is a dome of high-pressure air that is nearly stationary off the coast a couple of hundred miles. This stationary high forces the storm cells parading across the Pacific Ocean to the north of California and delivers them to Washington, Oregon and Alaska. In the fall this high-pressure dome disappears and both the high-pressure cells and the low-pressure cells are allowed to enter the state. The barometric winds rotate clockwise around a high-pressure cell (and counterclockwise around a low). In the fall, as a high-pressure cell moves in from the west, the wind blows from the desert to the east of us toward the ocean and sometimes the winds can be pretty severe. High-pressure usually brings nice weather, which translates to hot weather in the deserts. When this happens, the people in Southern California call the strong, hot, dry winds from the east “Santa Ana’s”. During the Santa Ana’s the fire danger goes from “high” to “extreme” in the coastal mountains and communities. During these times even the most mundane spark can create a firestorm of gigantic proportions. Every year the firestorms of central and southern California make the international news. Having lived most of our adult lives in the San Francisco Bay Area, we have been aware of the Santa Ana winds, but quite frankly the Bay Area is pretty much north of the phenomena. We’ve experience usual strong winds out to the east a couple of times when sailing and other times when we were aware of the winds but other than that we were oblivious. Here on the Central Coast, in the late fall, the Santa Ana are the focus of the print and television news and with due cause. This fall a southern suburb of Santa Barbara, Montecito, caught fire. Montecito is an upscale neighborhood with large, well-separated homes with lots of mature trees and plantings. The Santa Ana’s were blowing and the humidity was way down before the fire started. Once a fire like this one starts, particularly in area with steep sidehills, the fire creates it own wind. The sparks can jump ahead of the fire making firebreaks almost useless. The fire rages for several days. The press labeled it “The Tea Fire” (I have no idea why) and the television coverage was continuous; at least for the Santa Barbara station. It was pretty scary. Over 100 homes were destroyed. Several days after the fire was contained the first rains fell and the treat passed. Trying to anticipate the weather based on the local weather reports is a real crapshoot. Since the weather is prone to be different depending on your neighborhood, having the forecast be right is more a matter of being in the right place at the right time. This year, we had a little rain in the middle of November and December, but well below the averages. The rain was enough to curtail the “fire season” but soon the news started hinting at the possibility of drought. December and January left us feeling ambivalent – we enjoyed the beautiful dry weather, but feared the consequences of a too dry rainy season. February brought a change and the rainy season. We started getting a series of small storms that soon brought us to near normal. California is called the “Golden State” – originally because the discovery of gold was responsible for its rapid original growth. But, many people think that “golden” refers to the color of the hills when the grasses turn brown (golden). The spring rains bring on the green. With the rain the new grasses grow and the grassland turn a beautiful Kelly green. We are just now seeing a hint of green but there should be much more to come. |
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| A picture of the mountains to the East of Morro Bay taken in December after no significant rain in eight months |
| The same view taken two week after the first rain in January |