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That the climate on the Pacific Coast in California is extremely moderated is well-documented.
However, these cool nights astound me. How on earth can these ultra-moderated climates that normally (at least in Western Europe) are associated with low diurnal variation have so cool summer nights?
August average lows on or near the Pacific:
Monterey: 53.1/11.7
Salinas: 55.3/12.9
Santa Cruz: 53.9/12.2
Half Moon Bay: 52.7/11.5
San Francisco: 55.1/12.8
Fort Bragg: 49.4/9.7
Eureka: 52.8/11.6
Crescent City: 50.9/10.5
Given their latitudes, you'd imagine that nights should be 5 C warmer and much lower differences between days and nights.
This is contrasted by well-moderated west coast climates in Europe, Swedish isolated islands et cetera in terms of average lows.
My theories are twofold:
1) The water temperatures are such exceptionally low that they really need the daylight to get the temperatures to rise.
2) The summer nights are longer than in Northern Spain and in particular insular Sweden and the early sunrise at a maritime place keeps overnight lows at say 5 am much milder.
How do you lot explain the cold-ish lows at these super-maritime areas?
That the climate on the Pacific Coast in California is extremely moderated is well-documented.
However, these cool nights astound me. How on earth can these ultra-moderated climates that normally (at least in Western Europe) are associated with low diurnal variation have so cool summer nights?
August average lows on or near the Pacific:
Monterey: 53.1/11.7
Salinas: 55.3/12.9
Santa Cruz: 53.9/12.2
Half Moon Bay: 52.7/11.5
San Francisco: 55.1/12.8
Fort Bragg: 49.4/9.7
Eureka: 52.8/11.6
Crescent City: 50.9/10.5
Given their latitudes, you'd imagine that nights should be 5 C warmer and much lower differences between days and nights.
This is contrasted by well-moderated west coast climates in Europe, Swedish isolated islands et cetera in terms of average lows.
My theories are twofold:
1) The water temperatures are such exceptionally low that they really need the daylight to get the temperatures to rise.
2) The summer nights are longer than in Northern Spain and in particular insular Sweden and the early sunrise at a maritime place keeps overnight lows at say 5 am much milder.
How do you lot explain the cold-ish lows at these super-maritime areas?
I could be wrong but I think it's because of the cold Pacific Current, and how much the semi arid/arid US Southwest heats up during the summer.
Location: Live:Downtown Phoenix, AZ/Work:Greater Los Angeles, CA
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It's the marine layer, most days, it moves in at night all the way to the coast ranges. And will cool temps down to just below the sea water temp.
In fact, I just drove into LA overnight from Phoenix, and was already hitting the marine layer clouds and fog by the time I got to Cabazon towards the west end of San Gorgonio Pass
My area gets the same summer lows, but has warmer sea temperatures. A cold summer night can see the air temperature 16-17C colder than the sea temperature.
Probably a different situation to California though, Marine air doesn't flow inland at night here - it flows offshore (landbreeze). A common sight in the morning here, is towering cumulus 20-km out to sea. That's from the warm air rising off the sea, which then draws air from land, combined with a downslope effect.
Also SE airflows producing conditions for rapid raditive cooling, which is when the very coldest summer nights happen.
Warm nights here usually only happen from subtropical lows.
For California, I think the sea breeze causes low maximums, and longer nights give more time to cool off.
Location: Live:Downtown Phoenix, AZ/Work:Greater Los Angeles, CA
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Reputation: 9169
Quote:
Originally Posted by Joe90
My area gets the same summer lows, but has warmer sea temperatures. A cold summer night can see the air temperature 16-17C colder than the sea temperature.
Probably a different situation to California though, Marine air doesn't flow inland at night here - it flows offshore (landbreeze). A common sight in the morning here, is towering cumulus 20-km out to sea. That's from the warm air rising off the sea, which then draws air from land, combined with a downslope effect.
Also SE airflows producing conditions for rapid raditive cooling, which is when the very coldest summer nights happen.
Warm nights here usually only happen from subtropical lows.
For California, I think the sea breeze causes low maximums, and longer nights give more time to cool off.
California sees a predominantely onshore flow due to the deserts and inland valleys heating up more than the coast, that air rises starting the convection cycle, and then cooler marine air is pulled in underneath it. This cycle mainly happens in Spring and Summer, in Fall and Winter, the flow reverses as the deserts cool off faster than the coast, and offshore winds develop causing coastal SoCal's katabatic 'Santa Ana wind'
Marine layer is most prevalent in late spring and early summer, when there is the greatest negative deviation in temps between the coast and the desert
California sees a predominantely onshore flow due to the deserts and inland valleys heating up more than the coast, that air rises starting the convection cycle, and then cooler marine air is pulled in underneath it. This cycle mainly happens in Spring and Summer, in Fall and Winter, the flow reverses as the deserts cool off faster than the coast, and offshore winds develop causing coastal SoCal's katabatic 'Santa Ana wind'
Marine layer is most prevalent in late spring and early summer, when there is the greatest negative deviation in temps between the coast and the desert
Yep, the inland heat of Northern California is much different to here or Western Europe.
The sea temperature in all of those places listed is actually colder than I had thought, at only 1-2C warmer than the air temperature, so temperatures are what could be expected.
I'm more interested in places that have a bigger gap between average air minimums and sea temperatures. Comparing my town to Crescent City (same latitude)shows CC with summer air minmums less than 1C colder than the sea temperature, while here has 7.2C. In winter CC has a 6C difference, while here has 11.5C difference -easy to see which is more oceanic moderated, although if average air temperatures are used, here has only 1C difference between air and sea temperature during summer, while CC has 3C in summer.
Last edited by Joe90; 09-05-2016 at 10:57 PM..
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