Looks like you've got a variety of white oak with those lobed leaves ...and given those leaves look to be primarily intact/whole and not discolored (with whites, dark browns, or other non-typical leaf transition colors) that'd seem to rule out most common oak tree diseases listed here:
Several common types of oak tree disease exist, including oak leaf blister, oak wilt, leaf...
homeguides.sfgate.com
Also means that since it's a species of white oak if it were to acquire oak wilt - (which it doesn't seem is something that easily acquired - from
Oak Wilt 101 — MichiganOakWilt.org: "Oak wilt (
Bretziella fagacearum) gains admission to oak trees via root grafts or through wounds.
In other words, the oak wilt (OW) fungus cannot actively penetrate and infect trees as many other fungal pathogens or pests can. After gaining access to trees via wounds or through root grafts from nearby diseased trees, the OW fungus infects and then inhabits the vascular tissues where it basically colonizes the entire vascular system of the tree. Within weeks after infection, trees in the
red oak family usually exhibit symptoms of leaf loss and death, previously discussed." -- emphasis added)
- that it wouldn't be dead in a matter of weeks. Though it also doesn't seem like it matches oak wilt (from the leaves at least), so unless there are open wounds, cracked bark or the pressure pads associated with oak wilt (examples can be seen by searching "oak wilt pressure pads") ..it's probably not that either.
So given it's already September and I'm neither an arborist nor local to your area (so don't know what the weather has been like for the last few months) .... I think I'd still chalk it up to the tree just going through it's normal cycle of dropping leaves for the winter (perhaps a tad earlier than others if the immediate/local conditions put some sort of slow/long stress/competition on it).
Though if it's a significant concern getting a local arborist to look at it may be worthwhile as they'd be far more informed on conditions and diseases in the local area (and able to see any other considerations that could be at play).
Just my $0.02 though....