Have you ever considered buying one of those big inflatable palms that are sold in most novelty shops, and pinning up a few beach posters? That might help!

Also, maybe if you leave things lying around, like sandals and a big floppy straw hat you may be able to trick your brain into thinking it is summer.

The last thing I can think of would be to burn candles. Choose scents like melon and lilac. I've heard that smells cause the strongest memory recall.

Just an idea,

-Fleeing Bellocq