Lee Poulsen
Fri, 07 Oct 2005 14:47:12 PDT
On Oct 7, 2005, at 10:39 AM, Angelo Porcelli wrote:

> Lee, thanks for the useful links but I need to make a few more 
> precisation.
> Apulia is the longer region of Italy and climate isn't uniform moving 
> from north to south and especially from sea to inland.
> Localities like Monte S.Angelo and Foggia are very inland and cold. I 
> live close to Bari anyway, just on the sea. The sea belt has a 
> different microclimate and temps are a couple of degree (1F) higher 
> than that table, which values are taken from Bari airport (inland). 
> Ok, it's not a matter of a degree more or less, but we do have in July 
> temps over 90F regularly (was 113F some years ago !) but speaking of 
> averages in long term (i.e 30 years) these odd values are smoothed 
> from the cool summer like the past one, which has been a kind of 
> British one !!


You are quite correct. Here in southern California, we also have quite 
the variation between coastal and inland temperatures even over the 
space of distances as short as 30 km. Also there can be quite a range 
of elevation in that short distance as well. I noticed that this is 
true of Italy as well. This will also produce quite a difference in 

Like I said, those sites are the best I've found so far for free 
climate data. If you can get access to the full weather data sets of 
each country (which typically costs money), you can find out all kinds 
of other parameters. But the most easily available is the long term 
average monthly max and min temperatures. Since they average the 
highest temperature reached each day of the month together and they 
used typically 30 years worth of this information, they're averaging 
the max. temperature for 30 (years) X 31 (days) [for a month such as 
July or August] = 930 numbers into one value in the table which 
represents an entire month. So yes, cooler years will counteract the 
effects of the hotter years.

Pasadena seems similar to Foggia in that our 30-year average max 
temperature in July or August is about 89°F. And yet, it often is in 
the 90°s, and sometimes gets into the mid to upper 100°s, but in the 
long run, we also have summer days where it stays in the 70°s. This 
never happened in my home town where I grew up--Austin, Texas. It was 
always hot every day in the summer. And the average max temperature 
there in July and August is something like 95-96° F.

On the other hand, unlike Apulia, as you get closer to sea level and 
the coast--which is only 30 miles from where I live, the weather gets 
noticeably cooler. At LAX (Los Angeles Airport) which is only one mile 
inland from the coast, the average max. in July and August is 76°F. 
They can easily grow fuchsias near the beach in southern California, 
but it is much more difficult to grow them well inland, but still 
possible here in Pasadena. And in Austin, Texas it's impossible; they 
die during the summer no matter what I did.

Generally speaking, in the Eastern U.S. they have much more uniform 
temperatures over long distances than in the Western U.S. In the East, 
typically, 30 miles makes little to no difference in the temperature 
(except along the immediate beach coastal area), whereas in the West, 
the temperature can easily change by 20°F within a 30 mile distance. In 
some places, like the San Francisco Bay Area, you can have incredibly 
large temperature differences in very short distances without any 
change in elevation. One of the most drastic ones I've witnessed on a 
number of occasions is going through the tunnel from Oakland to Walnut 
Creek. The tunnel is only 2 or 3 miles long. But on some July or August 
days, during the middle of the day, it can be 65°F on one side and 
105°F on the other side.

Weather is interesting, especially if you grow rare plants.

--Lee Poulsen
Pasadena area, California, USDA Zone 10a

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