Charles Ellicott Commentary Jeremiah 36:22

"Now the king was sitting in the winter-house in the ninth month: and [there was a fire in] the brazier burning before him." — Jeremiah 36:22 (ASV)

Now the king sat in the winterhouse in the ninth month. —The “winterhouse” (the palaces of kings seem to have been commonly provided with such a special apartment) was probably the southern wing of the palace. It was in November or December, and, as glass windows were unknown, a charcoal fire, placed after the Eastern fashion in a brazier, or earthen pot, in the middle of the room, was a necessity.

So we find a fire in the court of the high priest’s palace in the raw early morning of a Passover in March or April (John 18:18).