Winter is approaching in the Northern Hemisphere - so . . .
Given:

• No or little wind
• Clear sky, no precipitation
• 10+ mile ride
• Level or near level
• Daylight
• Average speed 12+ mph

Or as many of these as your riding situation fits. (And, I am sure I forgot something above, which someone will kindly point out to me. )

So, what is the coldest temperature Fahrenheit you will ride in?

And, what secrets do you have about staying warm???