... whenever I go out, I ensure I have with me a sunhat, sunglasses AND an umbrella. I"m almost certain to need at least one of them.
... whenever I go out around lunchtime, I take OFF my fleece and hang it up in the house, as it's surprisingly warm out in the sun. Then when I get home, after about half an hour I'm chilly once more, so I put the fleece on again. It's taken nine years to get used to this feature of life here. In the UK we put jackets or fleeces on to go out, and keep the houses warm enough in winter that we can take them off when we get in.
... whenever I'm out anywhere, dressed in jeans and a warm sweatshirt (though probably not a fleece) I am still astounded at tourists from Western Europe who go around in tee-shirt, shorts and sandals. Even if the sun is out, and it's relatively warm when walking any distance, it's still only about 15-20 degrees Celsius at best.