My experience:

Temp (F) Wind MPH Wind Chill Clothing Assessment
66 5-10 65 Sweats, T-shirt Shorts would have been OK, except during gusts
60 7 59 Shorts, T-shirt Adequate
60 7 59 Sweats, T-shirt Comfortable
58 5 58 Sweats, T-shirt OK
58 10 56 Sweats, T-shirt Barely OK
56 5 55 Sweats, T-shirtx2 A little too warm
50 5 48 Sweats, T-shirtx2 Adequate
45 9 40 Sweats, T-shirtx2, hoodie, ski cap, cotton gloves OK
40 7 35 Sweats, T-shirtx2, hoodie, ski cap, cotton gloves Adequate
  • Note that T-shirtx2 = a long-sleeve T over a short-sleeve T
  • Note that “Sweats” = Sweatpants

Wind chill temperature = 35.74 + 0.6215T - 35.75V (0.16) + 0.4275TV(0.16)

In the formula, V is in the wind speed in statute miles per hour, and T is the temperature in degrees Fahrenheit.

Or calculate it at http://www.csgnetwork.com/windchillcalc.html