Bay Area Soil Temperatures Warmer Than In San Diego...Why?

[Jim in Los Altos]

According to this site, our soil temperatures here in the Bay Area are higher than those in most of Southern CA including San Diego. My guess is the nearly constant overcast nights and resulting mild temperatures and less radiation than in Southern CA this month where there have been more clear nights. Does that make sense or is something else going on. http://www.greencastonline.com/tools/SoilTempMaps.aspx

[Josh-O]

interesting Jim

[nachocarl]

Higher organic level and more vegetation?

[JEFF IN MODESTO]

Hi jim,

The map seems to be generalized but without looking at all the data I have a possible explanation.

It's been a much warmer than normal ( and wetter).

The ocean temps off the coast of San Francisco are 61f.

Even inland where I live air temps are much above normal with warm rain almost daily.

My normal temps at this time of the year are 55f/39f, so far this dec it's 61f/50f and my soul temps reflect the Bermuda like weather.

I have papaya trees in full fruit, hibiscus in full flower and I'm still picking ripe tomatoes.

Btw, my lowest temp so far was a mild 41f and we have had zero frost.

On the downside, we grow 90 percent of the countries stone fruit in this valley and we've only had a couple of hours of chill.

Jeff

[MattyB]

Really? I have a hard time believing that. Maybe it has to do with the angle of the sun and the fact that you guys get more daylight hours in winter. Or maybe it's because of all the rain you've been getting, mitigating soil temps.

[Jim in Los Altos]

Really? I have a hard time believing that. Maybe it has to do with the angle of the sun and the fact that you guys get more daylight hours in winter. Or maybe it's because of all the rain you've been getting, mitigating soil temps.

Matty, We're 500 miles north of San Diego so we have less daylight by several minutes and a lower sun angle this time of year. Our daylight is conversely longer in the summer though. My lowest temperature so far was 46F but most mights have been in the 50s and some in the low 60s. We've had 10'' of rain in December too. All my soil probe temperatures as of yesterday were in the mid 60s six inches down. Lots of my palms are actively growing still.

You guys down south have had quite a bit warmer daytime temperatures though.

[Jim in Los Altos]

Hi jim,

The map seems to be generalized but without looking at all the data I have a possible explanation.

It's been a much warmer than normal ( and wetter).

The ocean temps off the coast of San Francisco are 61f.

Even inland where I live air temps are much above normal with warm rain almost daily.

My normal temps at this time of the year are 55f/39f, so far this dec it's 61f/50f and my soul temps reflect the Bermuda like weather.

I have papaya trees in full fruit, hibiscus in full flower and I'm still picking ripe tomatoes.

Btw, my lowest temp so far was a mild 41f and we have had zero frost.

On the downside, we grow 90 percent of the countries stone fruit in this valley and we've only had a couple of hours of chill.

Jeff

Jeff, The rain and mild temperatures are a blessing to people like us but probably disastrous to orchard owners. This is citrus weather, not apple weather. I picked two mangoes and three papayas a couple of days ago and New Guinea impatiens are still in bloom and healthy as are all my coleus which normally are looking pretty tired this time of year.

[WestCoastGal]

That is an interesting comparison. We've had pretty warm rain for the most part, maybe that's holding in the heat underground as well as the warmer nights' air temps. It's been awhile since I've seen this many "big" cloudy days and nights. I know our yard is warmer this year do to composting and mulching. Conservation is up but doubt that many people are composting and mulching to warm the Bay area.

[David in Berkeley]

Jim, unless I'm missing something major, enlarging that soils temperature map shows all of coastal California from San Diego up to the Bay Area as having the same range of temperature, and doesn't give an exact temp for any one spot. So how does this indicate we're warmer?

[Jim in Los Altos]

Jim, unless I'm missing something major, enlarging that soils temperature map shows all of coastal California from San Diego up to the Bay Area as having the same range of temperature, and doesn't give an exact temp for any one spot. So how does this indicate we're warmer?

Dave, the map was updated yesterday. Enlarging it before yesterday still showed most of southern CA with cooler soils than up here. 60 degree plus soil temperatures are common along all of the central and southern coasts according to the update. Even that is unusual as far as I know. My own soils are low to mid 60s. Last year, at this time I was recording mid 50s.

[Josh-O]

Jim, stick a thermometer in the soil 6 inches deep in the same location every evening at 6:30 pm sharp. Do this for the duration of 1 month and make sure you document with accuracy and take plenty of photos..

Just kidding Thanks for sharing your scientific findings

happy growing!!

[Moose]

Well it certainly cools down in the desert more at night.

[John Case]

In my area, the lowest temp overnight (early AM) has been 46 degrees. This is very unusual for us as well normally, at least for the past few year, start dipping into the 30s in December. Also, the water in the Koi pond is still well over 50 degrees. Normally, I stop feeding the fish around the first of November when the water temps are under 50. I would imagine that soil temps follow this trend this year.

The rains this year have injected a lot of heat into our area as they have ben more tropical in nature (Pineapple Express), so this may have been contributing to the higher temps,

I do not know why, so do not take my next statement seriously.....I love global warming!

JC

[Josh-O]

I love global warming too!!

Soon you Nor-cal folks will be shipping us So-Cal peeps coconuts..hahahah

[Pando]

Thanks JIm, that's a nice resource! I think it's great to monitor this throughout the year and compare.

I think that this 5 degree gradient on the map is a gross average over a large landmass, and local microclimate variables probably play a larger role here. For example, someone in SoCal on a south-facing hillside with large boulders around or close to the house can probably see higher soil temperatures than someone in NorCal in a valley. For this reasonI think it is probably very useful for weather forecasters and large scale farmers, but perhaps it's less accurate to backyard gardeners.

[Josh-O]

I'm not a big theory guy but I'm liking all the thought behind this thread