To convert Fahrenheit to Celsius, we can use the formula:

°C = (°F - 32) × 5/9

Plugging in the Fahrenheit value of 99.4, we get:

°C = (99.4 - 32) × 5/9

°C = (67.4) × 5/9

°C ≈ 37.4

Therefore, 99.4°F is approximately equal to 37.4°C.