That's the way 1Weather works. I have it set to update every fifteen minutes on my Moto X.Shouldn't any weather widget that allows you to choose the update interval be easy on battery? I use Transparent Weather or something like that because I like the widget's style - I have it set to update once per hour and if I open the app itself (not just the widget). Doesn't seem to have a bad effect on battery life.
I had Accuweather for awhile and dumped it after a week. That was some time ago and I don't remember why.I like Yahoo Weather. I used Accuweather and didn't find is Accu. I don't have a battery problem but I don't know if either is a hog or not.
No matter which one you pick if you can not control how often the widget updates you will not have much control over battery usage. I have been using Google Now for my weather needs because widgets use more battery no matter which one you pick.