Below zero: Ice if there's water to freeze, wrap up. (If double-digits, it's probably already in the midst of visible snowfall, so visually assess the wisdom of being outside.)
If I had to split, high single-figures is bitter, low single-figures quite manageable.
Single digits (positive): Nippy. Try to remember gloves. Have pockets without too much other stuff stuffed in so that hands can go in there intermittently (if no gloves) or gloves can go in there intermittently (when I'm happy about my hands, and/or need them unfettered).
High-single digits can even feel quite balmy, if we've just had a cold-snap.
10s: Golden zone. A bit cool at the extreme lower end, a bit too warm at the upper end, but "normal". Clothing depends mostly upon air movement and any precipitation, with little regard for temperature for most of the range, but will often be a shirt/T-shirt with light jacket/blazer (according to situation) until it gets uncomfortable with the top layer.
20s: Invariably too hot. There aren't layers I can really shed, once I'm down to the (T-)shirt. I have a light UV-proof walking shirt laid away especially for just such occasions (as primary and sole layer, that is; it's also occasionally my secondary layer around the 15°C time, when it's sunny and endangers my arms). Low 20s are sufferable, High 20s are insufferable.
30s: No. No no no no no. No no no no NO NO NO. NO!
- Definitely no fun. If I can dive into a Server Room for as long as possible, I will. I have never enjoyed the high-30s, when they've happened.
For reference, I had a brief check of various thermometers I have laying around the house (analogue and digital - rarely actually checked, but inbuilt into devices like clocks and other mostly forgotten items I had once plotted data from) and I'm working at 13 (floor-level ground floor) to 15 (eye-level, first floor1
) degrees in light clothing, and am about to put on a jacket, a different pair of trousers (mostly for the pockets) and shoes in order to head out to a shop through air that various forecasts pegged at 8°C. Haven't decided about the gloves, yet. (There'll be a hat. There's nearly always a hat, atop my head or stuffed in my waistband ready for deployment. Sun, rain, wind or snow. It keeps my hair dry, my eyes less blinded by the sun, keeps my hair unruffled by the wind (though not unaffected by the hat) and my choice of jacket deals with my torso and, especially, shoulders.)
I'm old enough to have
used °F in my youth, but have since lost the vital mental imagery of things. I still think in stone for body weight
, so both kg (most of world) and
lb (US) body-weights need me to perform some arithmetic. Otherwise, I'm mostly metric with most things when it isn't doorstep-milk, pub bitter or road distances.1
I'll let part of the world puzzle about that, coming from their own illogical system.