Beverly is accessible year-round, but the most comfortable visiting months are May through October. Summer brings warm weather and occasional events around the harbor; fall is pleasant with less humidity and colorful foliage nearby. Winter visits work fine if you're focused on the indoor historical sites, but some house museums close or reduce hours between November and April — check with the Beverly Historical Society before visiting out of season.
The proximity to Salem means Beverly fills with spillover visitors during October when Salem's Haunted Happenings festival runs. If you want a quieter experience of the colonial history without the Halloween crowds, visit in September or the first days of October.