What is my arborday.org Hardiness Zone?

Some zip codes are in small areas that are warmer or cooler than the surrounding area. These areas, called microclimates, are often associated with urbanization or steep elevation changes, and many are too small to show on our map.

If it looks on the map like your zip code should be in a different hardiness zone than the one we provide for you, your zip code is probably in a microclimate that is too small to represent on the map.

A good example of this is Chicago, Illinois. Several zip codes for the city of Chicago bring up zones 5–6.

Microclimates occur in most large cities due to the urbanization effect that buildings bring about. In addition, regions of the country with bodies of water or mountains may contain “pockets.” These climatic pockets mirror warmer or cooler zones than the surrounding region.