When Does Spring Arrive in Maine?

Meteorological spring in Maine begins March 1, but phenological spring (visible green-up, thaw, bird return) typically arrives:

• Southern Coast (Portland): Late March – early April
• Central/Inland (Augusta, Bangor): Early – mid April
• North/West (Aroostook, Mountains): Late April – early May

Snow can persist into April (or May in north). "Mud season" (thawing ground) is a distinct late-winter/early-spring period. Last frost dates range from early May (coast) to early June (inland).