This is interesting service where you can compare using the graphs provided the weather from various weather providers in some major cities. http://weatherchecker.org/
This is very interesting, because sometimes when you watch the weather forecasts from different companies it’s discouraging that they are quite different from each other. And it’s not clear whom to believe to. This is especially annoying when planning long trips, when you need to bring a raincoat, warm sweater and waterproof shoes when focusing on one provider, and if you focus on the other - the sunscreen and sunglasses. It still shows few cities and compares weather for today and few past days, but it is enough to have overall high-level picture.
To be able to see and compare the weather you can choose from drop-down list the city and the desired dates.