Q: I don't give a crap about when I should stop wearing white pants. The more important question is: when can I start wearing tweed?
A: We've found that Mother Nature offers sound guidance on when to break out the tweed: first frost. According to the Old Farmer's Almanac, on average this happens in Green Bay on October 4. This feels just right for us, as it's also the time we move exclusively to brown liquor. For most of the rest of the country we think the Almanac's first frost table will function as a fairly accurate tweed-wearing guide too.
If you live in a climate where frost is rare, you can start wearing tweed as soon as it's gloomy at least three days in a row.
If you live in climate where it never even gets gloomy, you either own no tweed or your love for the fabric is so irrational you will have no use for practical advice like ours.