I know it's a strange headline! but you must always consider the weather when having a bet on the Rugby. Especially in northern hemisphere, where the weather can change rapidly. A bright sunny morning in Limerick or Edinburgh and quickly turn into torrential rain and gale force winds by late afternoon.
Poor conditions like this will make handling more difficult and kicking a nightmare. Errors will lead to a stop start game and no team will be able to get into a flow.
Don't back big scores in rugby matches when the weather turns nasty. Also look for unfancied teams against French opposition in the Heineken Cup when the weather turns bad, horrific conditions can be a great leveler.
Strong winds will play havoc with teams that like to kick for territory, depending on the direction of the wind you might also see one team forced to run the ball more than they would like. You can use this to your advance on betting exchanges like Betfair Bookmakers, Betfair have lots in-play markets. It's much more likely that the team with a strong wind on their backs are going score the next points.