interactive map of zones, last frost-free date
At this site, there is good info on how they determine zones and frost-free, and last planting, etc.
About 1/3 way down, you can click on Interactive map, and cool - it zooms in on yr zip code and you can see clearly which zone you are in.
Of course also consider yr micro-climate. with me for ex, where I live and where I garden are 3 miles apart, both are zone 7a. But in the community garden frost comes much earlier than in the town.
I get weather-data addicted this time of year, itching to see when I can plant my annuals.