A lot of people still believe this but it just ain’t so. There was some validity to it long ago, before refrigeration, when oysters headed to market were more likely to spoil because of the warm weather. And back then, oysters were wild-harvested and there was a greater chance of them being contaminated with red tide or or bacteria, which flourish in warm water. With today’s regulated farming techniques, oysters are monitored for contamination. And, of course, they can be kept nice and cold from ocean to table.
Safety aside, however, some oyster aficionados stay away from oysters from May to August because of the taste–they claim that cold month oysters are tastier and plumper. Be that as it may, don’t let the time of year deter you if you are jonesing for oysters.