Invasion of the Summer people

At this time of year the Summer people start to invade. You know who I mean--the guys in t-shirts and shorts when everyone else is at least wearing a jacket. Ladies with their belly-buttons (and everything else) showing. Their numbers increase slowly.
The Winter people, meanwhile, go about their business in ski-jackets, gloves, scarves wrapped around their fragile throats, and heavy gloves. For a while, there is a mix, people dressed as Eskimos vs. those dressed as South Seas Islanders. Gradually, without a shot being fired, the Summer people drive out the Winter people, except for a hardly few who still war their hats, scarves, and turtlenecks.

In the Fall, the process reverses itself. On the first day when the thermometer falls below 60, the Winter People are out in full array, wool hats pulled snugly down to their eyebrows. The Summer people are in the majority, but are clearly on the run.

The Rain people carry an umbrella even if the rains has been stopped for half an hour, or if there is a light mist. The un-Rain people don't consider anything short of a downpour as rain. They leave their umbrellas back in the car because it's not really rain, just a little drizzle. In England, where it is usually raining at least a little, the contrast is most noticeable. If everyone is carrying an (open)umbrella, you know it is a gale force hurricane.