Cold Winds from Siberia
In winter, low pressure develops on the Sea of Okhotsk, and high pressure develops in the Asian continent.
This is the typical atmospheric pressure pattern in winter described as "high in the west and low in the east".
When this type of atmospheric pressure pattern develops, cold winds blow from Siberia over the Sea of Okhotsk.
The Sea of Okhotsk is rapidly chilled by the cold winds from Siberia.