Perhaps walking in California, but not walking in -40 with wind chill shearing your face off.
Which suggests that -40 with windchill is a relatively uncommon condition.
A half-hour walk in 20F weather is perfectly comfortable with decent clothing (an insulated jacket, wool socks, long johns under one's pants, a scarf), and that's about as cold as it gets in most of the inhabited world.
On the other hand, a walk in California can be pretty uncomfortable due to the beating sun & high-speed traffic situation in many areas.
-40 is uncommon, but "-40 with windchill" can mean something different. In Canada it's common to report the temperature along with a lower number that takes wind chill into account. Thus a weather reporter might say, "-25 (Celsius), -40 with wind chill", meaning it's windy enough that if you go out walking it'll feel like -40 and the creativity won't exactly flow.
This became standard about a generation ago. I believe they started doing it to alert people to the risk of frostbite. But every time I hear it I can't help thinking that previous generations of Canadians would look down their possibly frostbitten noses at us for weakness.
https://blog.fitbit.com/50-states-no-excuses-see-which-state...
I worked a physical job, stocking books and filling book orders for a summer while in college[1]. I used a pedometer and rarely went much above 10k steps (for the 8 hour shift anyway). That's walking basically for 8 hours straight (with stops to place or grab a book).
[1] - not my only physical job, but the one I walked the most, and the only one I ever had a pedometer on.
Despite how it might subjectively seem, its not anything even approximately like walking 8 hours straight if you don't get over 10k steps; a fairly average walking pace is ~80 steps per minute, for 8 hours that works out to 38,400 steps.
Well, yeah, you'd kind of expect that with active Fitbit users.
> so I wouldn't expect a significant drop with the weather.
I would, though I'd expect it to be less than you'd see from more casual people. Conscious effort doesn't completely negate the effects of convenient opportunities vs. adverse conditions.
"No such thing as bad weather, only bad clothing." (Swedish saying I was told)
People who want to be outside have good boots and down-filled parkas.
I'd venture that anything down, say -10C (15F), assuming moderate wind, doesn't cause much real problem for walking.
If you want the least pleasant weather for walking I'd say half a degree above freezing and pouring rain wins every time.