Two people have jumped from the observation deck of the Empire State Building, intending to commit suicide, and survived.
The first was Thomas Helms, a 27-year-old artist from Hawaii. He jumped on Dec 22, 1977, but the winds blew him onto a ledge 15-feet below. After lying stunned for a while, he managed to crawl back inside through a window.
The second survivor was Elvita Adams of New York City. She jumped on Dec 2, 1979, but again the wind blew her back toward the building, depositing her on a balcony on the 85th floor. A security guard noticed her there and pulled her back inside.
For whatever reason, the case of Elvita Adams attracted more attention. It inspired an off-Broadway one-man show, "I've Been Elvita Adams," which didn't get good reviews
Based on these two cases, windy days in December would seem to be the best days for surviving a jump from the Empire State Building.
Bridgewater Courier-News - Dec 23, 1977
Provo Daily Herald - Dec 3, 1979