Yeah, we have fixed another issue that caused spikes even when it is not going below freezing. That is probably what you were seeing. There is not currently a way to remove the spikes other than downloading the CSV file, editing them out manually, and then we could replace the file. Might be more pain than its worth, but I could support if you wanted to do that.
And yeah, I am really liking Discourse too, especially for the price! Open source FTW!