It doesn’t matter if it rains on your outdoor furniture. The constant moisture from the ground is worse. Especially if the moisture is in contact with the end wood of the table and chair legs, which absorb 10 times more moisture than the planed sides of a board.
If you want to keep your outdoor furniture for a long time, this is where you can make the most important contribution. The Bucket Lid Trick is well worth trying. Put a paint bucket lid under each leg. Add oil and let the wood soak for a day or so.