While tradition (and many others) says you probably shouldn't wear a tie without a suit, blazer, or sport coat, I'll admit that it's one of the rules I break sometimes. I've written before about mixing more casual shirts (and a tie) with more sporty jackets, and I'll probably do it again at some point in the future. There are days where I require at least a thin extra layer in the morning and after work, but barely leave the office during the day, and sometimes I find myself with this combination.
I fell into this look recently, during a week when work was a grind and the temperature was just a pinch below the heat oven it's been for months. It made even more sense given my bicycle commute.
It is summer, and a cherry red linen tie popped over a brightly-colored striped shirt. Showing a complete disregard for eyeballs everywhere was the lightly-colored glen plaid jacket over the top.
The jacket itself is a vintage (I'm guessing 60s or so from the tag) piece that I picked up years ago, and despite being lightweight, it's held up incredibly well (the talon metal zipper alone is massive and feels indestructible). It's not really a windbreaker and it's certainly not waterproof, but sometimes it's the perfect jacket for layering, tradition be damned.