We are thinking of going to angra at the end of June. Will the weather be ok? Will we be able to swim?
The water will be a bit nippy, but you can swim. Sea Temperatures:
Don't go to Brazil without a yellow fever vaccine, the Centers for Disease Control and Prevention (CDC) warns.
Four travelers have died from the virus. Even areas near big cities are affected.
pick carefully where you stay in AdR.... downtown is not a beach area...
people either go to the resorts along the mainland coast, farther away from downtown AdR.... or go to the island of Ilha Grande, which is part of the municipality of AdR.
AdR, other than resorts, is usually only a base for boat day trips... the bay has many islands, that is where most top beaches are located..
and, as referred in comment above, AdR is the municipality most hit in state of Rio de Janeiro by the current yellow fever outbreak... there have been 48 confirmed human cases in AdR alone this year; of which 14 people died (including 4 unvaccinated foreign tourists).
a somewhat mitigating factor is that peak YF season in SE Brazil (where state of Rio is located) usually runs till May... as winter and dry weather moves in, there is less mosquito activity and hence less YF transmission... but that does not equate to zero risk.