Why when looking for a weather forecast on-line does one site say one thing and another site say another?

Question

Why when looking for a weather forecast on-line does one site say one thing and another site say another?

Answer 1

A lot of sites have the forecasts generated by a computer program, and those programs vary from one site to another.  There are many different forecast generation programs out there.

Answer 2

Because forcasting isn't an exact science, its more of making educated guesses.

Answer 3

Because some people are looking at a different computer model than others, or are interpreting the data differently than others. Also some people don't look out the window, and just look at the computer model.