[evanb]

If you know the stops of the 6 train in Manhattan, the trick is that the stops are in Fahrenheit starting at 33rd street = 0˚ C. Each stop up town is +5˚C. Stays within 1˚C until 110th street.

[gowld]

So, every 9 streets from 33rd?

[evanb]

Not quite.

The stops are 33, 42, 51, 59, 68, 77, 86, 96, 103, which can also be read as ˚F.

The exact conversions are (˚C) 0.555, 5.555, 10.555, 15, 20, 25, 30, 35.555, 39.444 (I terminated the decimal repetitions, obviously)

The rule of thumb of 5˚ per stop is 0, 5, 10, 15, 20, 25, 30, 35, 40.

Note that eg. 51-59 is 8 blocks, 86-96 is 10 blocks, 96-103 is 7. But the rule of thumb is nevertheless good to ~half a degree ˚C the whole way.