To convert -15 degrees Celsius to Fahrenheit, you can use the following formula:

°F = (°C × 9/5) + 32

Substituting -15°C into the formula, we get:

°F = (-15°C × 9/5) + 32

°F = (-27°C) + 32

°F = 5°F

Therefore, -15 degrees Celsius is equal to 5 degrees Fahrenheit.