It's the same old story with a new twist. The night before you're leaving on vacation, you've got the suitcase open on the bed behind you, and you're staring blankly into your closet, trying to figure out what to bring. Is a light jacket overkill? Will you regret not bringing a pair of jeans for cool nights? Some people say arriving unprepared is a good excuse to buy new things, but I'd rather arrive prepared and not waste vacation time searching for necessary items.
Now for the twist. Instead of checking the forecast—which, especially for longer trips, doesn't deliver the whole picture—and hoping for the best, you check Weather Underground's Trip Planner and get historical data for your dates and destination. The tool calculates the chance of rain, sun, clouds, and wind, and offers the average high and low temperatures for the dates you enter. So then you march back to your closet, select the right clothing for your trip, and even manage to zip up your suitcase without jumping up and down on it first. Or maybe you fill all the space you saved packing the right clothes with shoes.
Though I'm not packing yet, I tried the Trip Planner for my upcoming trip to the Oregon coast. Left to my own devices, I would have packed for a summer beach trip, with plenty of t-shirts and shorts. Now I know that I should throw in some sweaters too, but that I probably don't have to bother with the umbrella. The only ones who might be unhappy about this are the local shops that sell sweatshirts to chilly tourists.