In other cities, “jacket weather” is a meaningful phrase, as it suggests that there are days when, in fact, a jacket is not required.
That is not the case here.
In San Francisco, a good lightweight jacket is as compulsory as underwear and socks.
Your newest basic: the technically minded Equilibrium by Triple Aught Design.
No matter how warm the day dawns, no matter how promising the sun glints off the Bay — sooner or later, you’re going to need a layer.
The Equilibrium is that.
It’s built to be super breathable. Meaning: when it’s cold outside, it insulates. When it’s warm, it cools — none of that clammy, damp feeling you get from your favorite cotton disaster.
That’s thanks to Polartec’s Alpha material, which Triple Aught says is now the U.S. Special Forces’ insulating material of choice.
It thermoregulates, so you don’t have to do it the old-fashioned way: taking it off and putting it back on all day long.
And if you wear en route to, say, Hawaii, all you need to do is stuff it in its own pocket and stow it for the trip.
It’s as much as we could expect from a jacket.