To find the current temperature, you need to subtract the change in temperature from the temperature yesterday.
Starting temperature: 13°C
Change in temperature: -18.6°C
Current temperature = Starting temperature + Change in temperature
Current temperature = 13°C + (-18.6°C)
Current temperature = 13°C - 18.6°C
Current temperature = -5.6°C
Therefore, the current temperature is -5.6°C.