The conversion

59°C = 138.2°F

°F = (°C × 9/5) + 32, so (59 × 9/5) + 32 = 138.2.

As an outdoor air temperature, 59 °C sits in the hot 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.

Celsius to Fahrenheit either side of 59 °C.
CelsiusFahrenheit
54 °C129.2 °F
55 °C131 °F
56 °C132.8 °F
57 °C134.6 °F
58 °C136.4 °F
59 °C138.2 °F
60 °C140 °F
61 °C141.8 °F
62 °C143.6 °F
63 °C145.4 °F
64 °C147.2 °F

The other direction

138.2 °F converts back to 59 °C, which is the same relationship read the other way. Going from Fahrenheit to Celsius, subtract 32 first and then multiply by 5/9 — doing it in the other order is the usual mistake and produces a plausible-looking wrong answer.

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