i learned a warm-up exercise from a guit@r player when i was just a pup and still employ it in my twilight years before i practice or perform.
it's basically doing a chromatic walk up the neck on the G-string to the 12th fret, backwards to the nut on the D-string, up to the 12th on the A-string and back down on the E-string. Since you're at the nut (or open string) on E-string, repeat the exercise starting there up to the nut on the G-string. start slowly, intonate every note, pluck (or pick) in a steady tempo. Use all the fingers on your left hand. the purpose of the exercise is to stretch and warm up your hands, get them working together, not to see how fast you can do it.
as a youngster, it taught me the fingerboard by feel. now, as an old geezer, it gets my muscles and tendons warmed up before i dig in since i can't really feel the tips of my fingers on my left hand anymore.
for me, playing bass is a physical activity akin to working out. you'll be doing your hands and forearms a favor by warming up whether it's warm or cold wherever you are.
IMHO, of course, YMMV.
