[Ernest_at_the_Beach]

The temperatures in the article are given in Centigrade...the simple formula

... for temperatures above 0 degrees Centigrade ...

to be converted to Fahrenheit is to do C x 1.8 + 32 = F.

Thus 40 degrees C becomes 40 x ( 2 - 0.2) + 32 = 80 - 8 +32 = 104 degrees F...

Notice the use of ( 2 - .2 ) replacing 1.8 so that you can calculate it without use of a calculator.

[USFRIENDINVICTORIA]

Here’s the formula to use, if you visit northern Canada or Alaska in the winter:

-40* C = -40* F

To convert -50* C to Fareinheit:
Take the difference from -40* — in this case -10* C

Multiply by 9/5 (or 1.8) = -18*F

Add (-40* F +(-18* F) = -58* F

[reg45]

Celsius is actually quite easy:

• 0 - water freezes
• 10 - a cold day
• 20 - room temperature
• 30 - hot
• 37 - body temperature
• 40 - very hot
• 50 - extremely hot
• 100 - water boils

[JoeFromSidney]

For converting between Fahrenheit and Centigrade, here's an approximation that gives good results for temperatures in the "normal" range:

F = 2 x C + 30.

C = (F - 30)/2

Note that it works because you multiply the C by a number that's a bit too big, then add a number that's a bit too small. The errors tend to cancel. It's within a degree or two of the right number, and can be done in your head.