The dictionary defines vacation as "a period of suspension of regular activity, usually for the purpose of rest and recreation" ­ which certainly has a nice relaxing sound to it, but there's one crucial thing missing: weather. Isn't weather the very quintessence of vacation? Close your eyes and think vacationy thoughts ­ you're drowsing under a palm tree while soft, 80 degree breezes waft across the murmuring surf; or you're executing a flawless parallel turn in drifts of fresh champagne powder; or you're hiking through a sunny meadow, tanning on a dazzling deck, driving with the top down through someplace cooler, warmer, drier, wetter, calmer, breezier, but above all radically different from whatever weather you left behind when you suspended your regular activities. Vacationwise, weather is what makes it or breaks it. It's the magic ingredient in escape, the je ne sais quoi and the sine qua non of the perfect vacation.

So next time you're on vacation and you find yourself jotting the same trite phrase on every postcard ­ "Having a wonderful time, the weather's perfect" ­ don't be embarrassed. In vacationland, weather is never trivial: it's the front-page story every single precious day.

David Laskin comes to us from damp and dreary Seattle, Washington. The Weather Notebook is a production of The Mount Washington Observatory and is supported generously by Subaru of America and The National Science Foundation. Thanks today to Executive Engineer, Sean Doucette.