Since the demise of Weather Pulse years ago and the recommendation not to use gadgets, I've been searching apps that would display the outside temperature in the notification area. MajorGeeks has a free app today called YoWindow. I installed (carefully, declining the extras) it sandboxed. It's process was using 12,xxx kbs. Then I tried the Weather Channel's and it using 99,xxx, so it seems reasonably light. I actually haven't re-installed it yet but I probably will!