"In the trees in the shade it was extremely humid and well over 100iF. Out of the trees, in the cool Pacific breeze it was very comfortable and even COLD."

But you comparing apples to oranges. Replace the ocean with a sea of sand- then compare them. There many factors involved- and I wouldn't claim that the in the shade temperature reading in the desert would necessarily be warmer or cooler as compared to the in the shade temperature reading in the forest [but it's the shade offered by the trees that would lead me to EXPECT that the forest SHOULD be much cooler].
Another factor is the apparent temperature due to humidity. For example, I wouldn't be surprised if the humidity in a forest could be higher than on the beach or in the middle of a ocean surrounded by water- this because trees behaves like a swamp cooler- a typical tree can emit 40 gallon of water per day.

"If you ever find yourself in Iowa in the dead of winter try this experiment: Walk across an open field to a stand of trees...It doesn't need to be a big stand. I can guarantee you that it will be at least 5-10 degrees warmer in the trees than it is in the open field. The trees absorb the sunlight and are slightly warmer than the environment surrounding them. You will actually feel the "warmth" as it radiates out of the trees. If is very pronounced in pine forests especially where the leaves are dark, heavy, and hold even more heat."

Trees are living- living requires a chemical reaction [though some chemical reactions can rob heat instead create heat]:
"In thermodynamics, the word exothermic describes a process or reaction that releases energy in the form of heat."
http://en.wikipedia.org/wiki/Exothermic
And
In thermodynamics, the word endothermic describes a process or reaction that absorbs energy in the form of heat.
http://en.wikipedia.org/wiki/Endothermic

Ok, I would say that when a tree is using stored sugar [sap] it would involve a chemical reaction that produced heat [exothermic]. So I have no problem with idea that tree generate heat. Though it's question of quantity of heat generated. For example, a human being which is a warm blooded creature, is probably generating more heat than tree which many times more massive. So if you replace the tree with person standing in it's place [which could be a dozen feet apart from each other] the humans would probably added more temperature to the environment that the trees.

But you do bring up a point related Laurie Street's post about bugs and the hope that cold weather will kill them.