However, the salvaged Transocean Winner platform's temporary location in Broad Bay, Point, affords shelter from the worst of the southerly winds.
The rig was towed there after being pulled off rocks in Dalmore on the west coast of the island.
Four huge anchors are attached by heavy chains to the lopsided rig but additional weights are required to ensure it does not break free.
Three large salvage tugs babysat the rig while an anchor handling vessel, the MV ER Vittoria, steamed to Montrose to pick them up.
She returned on Sunday and will position the extra weights on the seabed so the the rig will eventually be held on by eight anchors.
Transocean anticipates keeping the rig in Broad Bay about the middle of September.
Additional heavy duty anchors are being laid to secure the 17,600 tonne oil rig which has been refloated after running aground in Lewis.
Anchor points will be doubled up to hold the damaged structure as bad weather returns to hit the Western Isles this week.
Wind speeds are forecast to strengthen later on Monday while gale force gusts and rough seas are predicted to affect the islands over the week.
Extra anchors for stricken oil rig
28 August 2016