Just yesterday I compared current winter (blue line) with previous one (orange line), current winter has been much warmer, although last winter was already pretty mild. The rupture in blue line in December was caused by defective batteries, that I bought in October, they depleted with 2 months (usually a set of batteries lasts ca 1 year). But missing part of the month was pretty constantly at +5C / 41F, so a way warmer than previous winter.