What climate factors keep Cal coast cool (San Diego, San Francisco: live, rated)

[Caleb0]

California has a really cool coast compared to the East coast (of the same latitude). Northern Europe for example is kept warmer than Canada by the Atlantic jetstream and this is well know. What weather phenom. keep the California coast extremely cool for it's latitude?

Also, I was looking through the almanac at some of the mid-coast cities (Morro Bay, ect) records and they would have random days in the summer (and fall) with records of 108, 112, ect, but the average is in the 60's-70's? How does this happen? Even in Dallas where I live which is normally 30-40 degrees hotter (it's been 100 20 something days in a row now) the record is usually 104 or so. How can the tempurature spike so much? Also, it is odd becuase the record might be 108 and the next day 91. So that means the temparature went up 20 degrees in one day then fell again, which seems strange to me.

[Gentoo]

Originally Posted by Caleb0

California has a really cool coast compared to the East coast (of the same latitude). Northern Europe for example is kept warmer than Canada by the Atlantic jetstream and this is well know. What weather phenom. keep the California coast extremely cool for it's latitude?

Also, I was looking through the almanac at some of the mid-coast cities (Morro Bay, ect) records and they would have random days in the summer (and fall) with records of 108, 112, ect, but the average is in the 60's-70's? How does this happen? Even in Dallas where I live which is normally 30-40 degrees hotter (it's been 100 20 something days in a row now) the record is usually 104 or so. How can the tempurature spike so much? Also, it is odd becuase the record might be 108 and the next day 91. So that means the temparature went up 20 degrees in one day then fell again, which seems strange to me.

We have a thread talking about the cold water off our coast. That's the driving factor that influences the coastal weather. Generally, as the inland heats up in summer, the warm air rises which draws in cooler ocean air. This creates a strong seabreeze and generally keep the coast cool. Sometimes however, other weather factors cause this pattern to break down and coastal temperatures will then soar. A high pressure sitting over the interior west can make all the difference in the world. It's exact position influences if the coast will get hot, how hot it will be and where it will get hot. If the high is north like over the northern rockies, places like Seattle will see hot temperatures while places to the south will remain mild. This is why you sometimes see an "upside-down" effect on the west coast with northern places sometimes being hotter. Place that high over southern Idaho then SF will get hot while SoCal still has nice weather. Let it slip a bit farther south then LA and SD get hot. Of course all this also depends on how big that high is. Also if the high shrinks a bit in size or slips east just a few degrees, the temperatures at the coast can change dramatically and quickly. Anyone who's familiar with San Francisco or even certain inner east bay locations knows what I'm talking about. It may have been in the high 70's or 80's for days. The new day may seem to be starting out to be the same. Then at some point a sea breeze comes out of nowhere and the temperatures drop quickly and abruptly and marine layer may suddenly appear out of no where.

[BRinSM]

the reason for the cool ocean breezes is because of the relatively cool ocean water. our ocean waters only exceed 70 degrees for a short period each year. r the water would be considered 'cold' by most people even in the middle of august, unlike places along the atlantic. the ocean currents in our little section of the world come from the north, where the water is even cooler. this gives the coastal sections of southern california some of the most temperate weather on earth.

[Gentoo]

Generally speaking, the current go clockwise in the norther hemisphere and counter clockwise in the southern. The western side of continents, especially in the mid latitudes tends to be next to cool water while the eastern sides of continents of the same latitude tends to be near the warm currents.

8(q) Surface and Subsurface Ocean Currents: Ocean Current Map

[roadwarrior101]

I would also add that lack of humidity is a driving factor for why you occasionally see extreme temperatures in coastal cities (although this typically only occurs for a day or two every 5-10 years). More humid areas back east rarely get above 100 or much above, since they're saturated with humidity. Compare that to the desert Southwest, where Phoenix may have 10-20 days in the summer that reach 110+. When there is a strong offshore wind blowing, the wind blows from the mountains to the coast. As it decreases altitude, this dry wind will pick up temperatures quickly and you may see temps approaching that of Phoenix on a rare occasion.

[Gentoo]

Originally Posted by roadwarrior101

I would also add that lack of humidity is a driving factor for why you occasionally see extreme temperatures in coastal cities (although this typically only occurs for a day or two every 5-10 years). More humid areas back east rarely get above 100 or much above, since they're saturated with humidity. Compare that to the desert Southwest, where Phoenix may have 10-20 days in the summer that reach 110+. When there is a strong offshore wind blowing, the wind blows from the mountains to the coast. As it decreases altitude, this dry wind will pick up temperatures quickly and you may see temps approaching that of Phoenix on a rare occasion.

You bring up another great point. Humidity is more uncomfortable but it actually moderates the temps, or at least prevents fluctuations. Sometimes however, those constant temps are uncomfortably high.

[Caleb0]

Thanks, all your responses answer the question enough as far as I am concerned. I remember one time I fly into Palm Springs and it was about 110 and drove to San Diego 2-3 hours (way quicker if the road was a straight line) and it was 55-60. Microclimates

[Gemdiver]

Originally Posted by Caleb0

What weather phenom. keep the California coast extremely cool for it's latitude?

California Current - Wikipedia, the free encyclopedia