World Weather Online

You may not know this but one of the inventors of the first electronic computer was a physicist with a passion for predicting the weather.  He figured that if he could just build an electronic calculator that was powerful enough he could use all the existing weather data and some special formulas to predict the weather.  It is therefore no irony at all that today we have quite a few super computers, all around the world, using electronic weather models to predict the weather. 
But how do you find the best and most accurate weather for our area?
You could start with the National Weather Service: Weather.gov/
Then there's a lot of commercial weather sites you could check out like these: 
Weather.com
Weatherstreet.com
Wunderground.com
Accuweather.com
Lifehacker.com claims that these are the five best weather websites. Maybe you should check them out too?

Outside the United States you could try the
And if that's not enough there's all those news websites that also offer weather forecasts.
As for which site is the most accurate, that will come down to old  fashioned trial and error on your part.  You'll have to check out some of these sites and see which ones you like.  Some things to look for:  easy to follow layout, easy to use, and accuracy.

PRACTICE ACTIVITY:   Check the weather online today and see which website is actually the most accurate.

TO KEEP ON LEARNING:  If you'd like to do some more research online about the weather try searching for:

Weather online
History of weather predictions
Weather models
Spaghetti models