...at least it is in Tucson, Arizona, according to this article from the Arizona Daily Star. I'd argue that any month is a good month to write a will if you don't have one.
The article reiterates much of what I say to my prospective clients: "This is the biggest kindness you can do for anyone.... Even if you think you have nothing to designate to anyone, put something in writing. Give them a hand. Let them know what you would want."
My own mantra is this: You may not be 100% certain about how and what you want to leave to your friends and family. As an estate planning attorney, it is my job to help you make these decisions. I believe that, in the end, these decisions are less important than leaving to your loved ones the gift of clarity.