I think it is very important to know the climate of the place which are you going to visit. First of all, because of the clothes. If you know the climate, you will take with only necessary clothes. Then you will have more free space in your bag. You will also know, which things are compulsory there. For example, if there is a hot sunny weather, you should take with suntan cream, if there is a rainy weather, you should take with your umbrella. Also you have to know the climate because of food. If the weather is hot, you can't take with perishable food (прим. perishable - скоропортящийся). And the last thing - you have to know the climate of the place which are you going to visit because of entertainment. If you want to have a weekend, you will not take with equipment for skiing on the seaside in the summer, won't you?