def windchill(temp, vel):
wc = 35.74 + .6215*temp - (35.75*vel**.16 + .4275*temp*vel**.16)
return wc

def main():
print (" __ __ __Temp /n")
print (" Speed /n")
print ("-20 70 10 0 10 20 30 40 50 60 ")

for x in range (5,55,5):
print x
for y in range (-20,70,10):
chill =windchill(x,y)
print chill + " "


main()

:mad: :cry: :o

Once more, please put your code into code tags to show the right indentation, see:
http://www.daniweb.com/techtalkforums/announcement114-3.html

Most people will not read any of your code unless you do that!

Your first program worked just fine, why did you change it?

This program will give you error, because you are giving it negative windspeeds! Use more meaningful variable names, t and v rather than x and y and you discover your mistakes!

Also newline is \n