The conversion

43°C = 109.4°F

°F = (°C × 9/5) + 32, so (43 × 9/5) + 32 = 109.4.

As an outdoor air temperature, 43 °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 43 °C.
CelsiusFahrenheit
38 °C100.4 °F
39 °C102.2 °F
40 °C104 °F
41 °C105.8 °F
42 °C107.6 °F
43 °C109.4 °F
44 °C111.2 °F
45 °C113 °F
46 °C114.8 °F
47 °C116.6 °F
48 °C118.4 °F

The other direction

109.4 °F converts back to 43 °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.