Question about seasons in Silicon Valley

[tstieber]

Originally Posted by mstnghu2

Actually the weather has changed. Even when I was in high school, I always remember May being warm to hot and very rarely rained. The hottest months were mostly from June-August. Over the last few years especially, May and June have been on the cooler side and have even had some rain.

September and early October have become increasingly warmer over the last few years also. It's as if summer is starting/ending later and later.

Several people seem to think fall has been getting warmer. I think it's been getting much cooler. Growing up in the 80s, and then attending college in the 90s, I remember 100 degree heat spells in early October many years, and 90 degree heat spells in mid-late October. I also remember wearing shorts on Thanksgiving numerous times in the 80s. The fact that we almost never break a heat record anymore these days is a sign of cooler temps IMO.

[mysticaltyger]

Originally Posted by tstieber

Several people seem to think fall has been getting warmer. I think it's been getting much cooler. Growing up in the 80s, and then attending college in the 90s, I remember 100 degree heat spells in early October many years, and 90 degree heat spells in mid-late October. I also remember wearing shorts on Thanksgiving numerous times in the 80s. The fact that we almost never break a heat record anymore these days is a sign of cooler temps IMO.

This is true at least for this year. So far in October, we're 2.5 degrees below the 30 year average month to date.

I've also noticed the last 4 summers have been cooler than average. Lots of days in the 70s. In the late 90s and early 00s, there were usually only a few days in the 70s in July & August and more 90 degree days.

[BayAreaHillbilly]

Originally Posted by mysticaltyger

This is true at least for this year. So far in October, we're 2.5 degrees below the 30 year average month to date.

I've also noticed the last 4 summers have been cooler than average. Lots of days in the 70s. In the late 90s and early 00s, there were usually only a few days in the 70s in July & August and more 90 degree days.

Broad brush: Growing up here the climate was warmer overall during my childhood (70s / early 80s). I left the area for most of the 80s and did not experience it continuously only visits. After my return there were a few warm years then it dropped (late 90s) and has never really recovered.

[marcopolo666]

Originally Posted by Brian B

What is fall like in Silicon Valley? Do the leaves fall off the trees?

To answer the question that was actually asked:

- for the deciduous trees, yes
- for the evergreens, no

Most of the deciduous trees are in the cities and suburbs, planted by the city. Most native trees are evergreens (live oak, sequoia. I left off firs and pines because although they are native to CA, they aren't native to the south bay (except in the mountains) and 'Silicon Valley' isn't in the mountains.

In general, as you are driving around the "more wild" (less developed) parts of the bay area you won't see a lot of trees losing their leaves. If you are driving through the sierras or the santa cruz mountains, you definitely will see that the vast majority of trees are evergreens.

In the cities, many trees change color and lose their leaves.

[mysticaltyger]

Originally Posted by BayAreaHillbilly

Broad brush: Growing up here the climate was warmer overall during my childhood (70s / early 80s). I left the area for most of the 80s and did not experience it continuously only visits. After my return there were a few warm years then it dropped (late 90s) and has never really recovered.

It's just one of those things...I realize a few years' worth of data don't give you the whole story. I also think the variation is because SJ is in the transition zone between the cool summer areas by the coast and the hot summer places in the Central Valley.

[drive carephilly]

It's funny to me when people argue about weather that already happened.

We've been collecting good weather data for ~140 years and most of the records have been online for at least the last 10 years. If you want to know how much rain fell at the airport in june of 2011 compared to may of 2003 just google it.

[KaaBoom]

Originally Posted by Brian B

What is fall like in Silicon Valley? Do the leaves fall off the trees?
Thanks

Yes, they do and they stay on the trees much longer. Some of the best fall colors I have ever seen are in the Bay Area. So I'd say we have a very long fall. Having grown up in the upper mid-west, my feelings are that San Jose has a distinctive three season climate.

Spring: Mid-January until Mid-April
Summer Mid-April until Mid-October
Fall: Mid-October until Mid-January

The definitions I use for the seasons:

Spring: Cool rainy weather. Flowers starting to bloom.
Summer: Warm/hot dry weather.
Fall: Cool weather, leaves falling off trees.
Winter: Snow/Freezing temperatures. (Obviously Winter just doesn't happen in the Bay Area. Though early January does get pretty close. Ultimately it just becomes a transition from Fall directly into Spring.)