Oh come on! You all make it sound like the Sahara with
water and mosquitoes.
I sailed for nearly thirty years on the Chesapeake, and while it can certainly get hot, you can reasonably cruise there in the summer if prepared for it.
My experience is that in general, August will be cooler than July but wind speeds may still be low. Be prepared to
motor. If the heat looks to hang in overnight, consider a
marine for a break, and use that AC. If there will be a breeze, and if the
forecast is for a reasonably cool night, find a nice anchorage and get the hatches open.
Yes, screens will be needed. Sometimes it's flies, sometimes mosquitoes, but most of the time it will be just fine.
Holding in the bay ranges from sand to mud to really sticky mud to clay. Occasionally, even sea grasses or shell beds. In most cases the holding is good, there are very few hard things to hit, though running aground was my usual pastime (though that was primarily from intentionally pushing the limits).
The Bay is one of the world's best cruising areas, especially if you have a new to you boat. Soft bottom, well marked, generally short passages, abundance of attractions as well as
safe anchorages. If something breaks, you have access to
parts and mechanics.
That being said, watch the skies in the afternoon. Copper-colored skies are an indication of imminent thunderstorms and these can be ferocious if you are caught unprepared. I usually planned to be stationary by 2 or 3pm on the days that were
forecast for storms. Short lived but frequently very dramatic!
Three and a half weeks is pretty short for
Nantucket voyage unless you plan to be underway most of the trip. On my boat, the Admiral likes to sample the local cuisine along the way. Speaking of which, be sure to partake of the local crabs, steamed, soft shell, crab cakes,
fish stew, etc. In fact, you could make a gourmet
survey of the Bay, traveling up the west side and back down the east
Get a cruising guide and jump in.
Tons of things to see and do on the bay. America's
history is everywhere you turn. Beautiful, quiet rivers and creeks. Populous areas if you so choose. Stay hydrated, watch the
weather and have a wonderful time.