The conversion

33°F = 0.56°C

°C = (°F − 32) × 5/9, so (33 − 32) × 5/9 = 0.56.

As an outdoor air temperature, 33 °F sits in the cold band. The other scale is on the dial beside it in the app, so a reading like this needs no conversion at all.

Convert something else

68°F

The range either side

Neighbouring values, for when the number you actually wanted was a degree or two away.

Fahrenheit to Celsius either side of 33 °F.
FahrenheitCelsius
28 °F−2.22 °C
29 °F−1.67 °C
30 °F−1.11 °C
31 °F−0.56 °C
32 °F0 °C
33 °F0.56 °C
34 °F1.11 °C
35 °F1.67 °C
36 °F2.22 °C
37 °F2.78 °C
38 °F3.33 °C

The other direction

0.56 °C converts back to 33 °F, which is the same relationship read the other way. Going from Celsius to Fahrenheit, multiply by 9/5 first and then add 32. Adding first is the usual mistake.

The full converter handles any value, in either direction, including kelvin, and shows the formula as it works.