Fullback Sam Fuller got the scoreboard ticking early on and the pack forced a penalty try soon afterwards, both converted by Simon Johnson.
Guernsey had plenty of possession and territory, but failed to take advantage with the elements in their favour.
On the turnaround Jersey scored at regular intervals, with Dan Lezala and the impressive Charlie Hubert getting the next two.
A yellow card for Jersey's Bryn Edwards did little to stem the flow and replacement Dominic Mayo and No. 8 Kaisa Leota made it 36-0.
Lezala then fed in Mayo for his second, before grabbing the final try himself, a score converted by Johnson.