Can global warmist’s such as Biden and Thunberg please explain to me that if global warming is “the most serious threat to humanity” why is?

Because Climate change affects winter weather too dummy!
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https://www.climatecentral.org/news/report-on-thin-ice-climate-change-shaping-winter-recreation

Do you know the difference between climate and the current temperature? Here's a few links. If you take the time to read them, you'll learn a lot about climate change.  https://www.un.org/en/chronicle/article/greatest-threat-global-security-climate-change-not-merely-environmental-problem

Are you playing dumb, or are you actually dumb?

Aside form the syntax errors (learn spelling and grammar); you've asked a question with inadequate data presentation. What is your location. Which hemisphere? What's your elevation? Is that 27 degrees Celsius or Fahrenheit? Is 27 degrees colder or warmer than usual? Is the weather system which your experiencing more or less powerful than usual? How fast is it moving? Which direction is it moving? Is THAT normal? Are the surrounding weather systems colder or warmer than usual? etc. 
For you simpletons, global warming won't effect the tilt of the Earth on it's axis, and so won't effect the seasons. If the weather is anywhere approaching seasonal, GOODY! What you can look forward to is huge weather events as the Earth's climate tries to stabilize. This has a tendency to result in droughts in normally lush environments, and egregious flooding in other environments. Remember a couple of years ago when US farmers couldn't start planting until mid-August? That's global warming.