A simple conversion I use is 16C X 2 + 32 = 64F (aprox.) Yesterday was in the low 80s however. Stay cool, Larry.
I just work it out in my head...
C to F... Multiply by 9, divide by 5, add 32.
F to C... Minus 32, times by 5, divide by 9 (or divide by 10, then add on a further tenth of that)
Gets you to within half a degree usually.