I worked at an office once where the wifi legitimately got worse when it rained. It was because the buildings internet used an antenna instead of being wired, and the building was just barely in range of the source signal. When it rained, it was enough added distortion to make it noticeably worse.
I have to constantly explain to my wife that if she can't reach a website it is likely on their end and there is nothing I can do until they fix it. I explain there is a chain of connections involved and me sitting and staring at her laptop for an hour isn't going to fix it.