This is one of the mature trees in our front yard, The leaves have all these circles on them. Fungal? bacterial? Will this be the result of our hot temps we have been happening with such high humidity and no rain? Will the tree die?????????

Attack of fungi. May be due to high humidity.
I assume that the tree will survive with no major problems.
When leaves will fall they need to be destroyed. Do not compost.

Eventually treatment with a fungicide. But it is difficult to a large tree. Because must be bathed completely.
I have no experience in America with treatment. Perhaps with a 3 in 1 solution based on Neem extract.
If it is rain the treatment is useless.

But it may not need treatment. If is a rainy weather very likely the sun will do the treatment. When time will be nice with sunshine.
Generally I avoid, as much as possible, to do treatments unless absolutely necessary.

This tree is about 50 feet tall. No way I can saturate it any way. Went to the local extension office with a handful of the leaves and quizzed them. Tar Spot, won't kill tree just aesthetically unpleasant. Due to lack of rain, high heat and humidityl Being in south Texas you would be used to the humidity. Wisconsin is not really. We have never had 90's and humidty in May/June. Mid August maybe a couple........

They also advised at burning our leaves from this tree instead of composting which has my husband in an uproar but oh well. He'll just have to get over it.

Thanks for your response. It is greatly appreciated.