Seeing as things are opening up, here are some flexible dates to travel to Lisbon. Full disclosure, I don't make any money off of these deals, and have no association with slickdeals or the airlines, I just happen to follow the slickdeals website often as I use it a lot to save cash on things I buy.
NYC Deal:
https://slickdeals.net/f/14966309-new-y ... march-2022
San Fran Deal:
https://slickdeals.net/f/14979158-san-f ... march-2022
Flights to Lisobon from NYC And San Fran (Nov 2021-March 2022 dates)
Moderators: Glenn E., Roy Hersh, Andy Velebil