My birthday is early October, and it is almost always nice weather.
I expect a last few weeks of warmth by end of September
Not a climate change denier btw!
I just don't see the point of people like OP getting themselves into an unhealthy mental state over something they, as an individual, cannot control.
I really feel for people with climate anxiety, every time it is unseasonably warm, or there is a heatwave, people now have panic attacks 
The panic attacks do not help the climate change pattern though. It makes me feel worried about people with anxiety 
Weather is changeable and weather is not the same as climate.
Today's warm weather is not necessarily a harbinger of doom, it's not that unusual for this time of year