Martin
Spam, wonderful spam (bloody vikings!)
As @RayofLight said, no matter what you do, you'll offend someone. But there are different levels of offense, I think. Paying someone a compliment is probably done with the best of intentions, and if they're offended by that, I wouldn't consider that anything to worry about. But deliberately upsetting someone on a personal level when they don't deserve it would be rather bad form, particularly if one did it repeatedly just out of mean-spiritedness.
Anyway, I'm British, and talking about the weather is our national obsession!
The weather is a nice, neutral topic for a chat. Better than talking about politics or religion, which often leads to irritation and swearing.
