I'm always cold. Always. It's my punishment for making fun of my mother (who always complained about how cold she was) for so many years. You will never catch me without a blanket, sweater or some other form of clothing that I can layer on to keep warm. I usually carry a spare too. Just in case. I know this advice will really bug you when your little. When you're young, your metabolism works much faster than us old people and you won't feel cold. I might nag you to wear your jacket in the wintertime but for the most part, I'll leave you alone. (Of course, I will always have something for you in case you do need it. That's what Grannies do. Just ask.) As you get older, you'll appreciate this warning.
Be prepared. Whenever appropriate, dress in layers and bring something to throw on in case the weather (climate) changes and you need to warm up. It much better to plan ahead and have something on hand rather than suffering without it. It doesn't really matter what season you're in... things change and you'll want to be ready.