Lol. Basically. As a local I’m bundled up way before other guests. But temps can vary by 20 degrees by day to night. We were at one of the Broadway series shows last year and everyone in my group laughed at me because I had hat, gloves and scarf jammed in my pockets and I had my winter coat on. At the end of the show, walking around World Showcase and back to the car. I was comfortable with all my winter garb on. They were freezing!
MANY a time on our Disneyland trips, it's been perfectly lovely in the middle of the day, but cool-ish early in the morning (where you need a light sweatshirt). And then once the sun goes down, the temperature drops a lot...and then when you factor in any sort of wind or a breeze, then it gets pretty darn cold!
On those trips when we're at DL at a time of year when it's cool-ish in the evenings, we bring light weight scarfs, light weight gloves, 1 hat per person, and a sweatshirt or jacket. Sometimes both if it's going to be especially cold in the evenings. Sometimes, we'll stash the extra clothes in a locker to use later in the day. And sometimes, we'll layer up with a long sleeved shirt as the base layer, a Disney t-shirt on top of that, followed by a sweatshirt, and then if it's cold enough, a jacket on top of that.
But usually, the long sleeved shirt, t-shirt, and sweat shirt is enough when you double it up with a hat, gloves, and a scarf.