8 years ago last frost date
It came to my attention it seemed every time I see my average last frost date it comes up as a different date.
|Average Frost Date (Seattle, WA)||Location|
|3/10||The Old Farmer’s Almanac|
|4/20||Victory Seed Company|
|3/22||Ed Hume’s Seeds|
|3/25||Clyde’s Garden Planner|
Now the humorous part of this is I didn’t go out trying to find as many non-matching dates as I could, these came in order from my Google query for “last frost dates”.
Under conventional wisdom, this number should be simply an average of the last frost dates for the past 30-40 years to give you about a 50% chance of avoiding frost given past history. So it seems really strange why these numbers vary so much.
Then I came across U.S. Climate Normals this site includes no only the dates but the probability of them being true. So if you are a betting man/woman (or just impatient) you can press your luck and plant with variable odds.
For my area (Seattle, WA) I have the following options:
|36 °F||Mar 27||Apr 11||May 18|
|32 °F||Feb 13||Mar 10||Apr 22|
|28 °F||Jan 01||Feb 25||Mar 20|