I realise your post was not specifically about climate change- but if you are going to base your assessment on long term historical data, then climate change automatically enters the equation. I think data from the last 10-15 years offers a better database than, say, the entire 75+ year record.

One other point, is that the body adapts to temperatures. If you are used to living in a climate-controlled environment (our urban existence with heating and air conditioning) you are going to be more sensitive to hot and cold. I am always amazed at reading about the old timers (John Muir and others) who did amazing trips with little gear. I think they were really adapted to outdoor conditions. Today, we softies are not!