Buckets of rain and oppressive humidity weren't enough to keep John Mayer fans from celebrating Born and Raised with the musician on the eve of the record's release Monday evening in New York City.
The man of the hour – toting an umbrella – greeted fans lined up outside of Reed Space on Orchard St., where a pop-up shop featuring photography and merchandise has been assembled for the week.
Mayer – who donned a t-shirt featuring lyrics to second single "Queen of California" once he spotted it for sale inside – mingled with friends, family and industry pals before settling down in the back corner with a pile of Sharpies, ready to meet the crowd gathered outside.
Admitted five at a time, hundreds of fans had their chance to greet the seven-time Grammy winner, who doled out hugs, posed for photos and signed everything from CD booklets to guitars.
Accepting letters and music, a mellow Mayer, 34, gave his full attention to each person who approached the table over the course of two hours.
"He looked like he was having a great time interacting with fans," an onlooker tells PEOPLE. "Especially since he won't be able to tour."
The Born and Raised Store will remain open through May 27, with a portion of proceeds benefiting NCIRE, the veterans health research institute Mayer supports.