I see what you're getting at HJ but the provinces, especially Leinster, don't seem to have a problem playing expansive rugby very successfully all year round. Plus Ireland's back play, over the last few years, succeeded at being dire no matter the weather.
The play for field position rugby is Kidney's style, with which he was very successful at Munster. With O'Gara in his pomp and it being his natural style Munster swept all before them. However Kidney stuck with the same conservative, play the percentages style when Sexton became the 10. Sexton's natural game is attacking with ball in hand. The new guys coming through (Jackson, Keatley, Hanrahan and especially Maddigan) are all comfortable playing with ball in hand.
Those guys have varying ability at playing the Kidney style of rugby. Ireland should be playing a style that suits the players available to us. Leinster play a very expansive style at a skill level that wouldn't look out of place in the NZ conference. Ulster's resurgence has been in no small part due to their willingness to attack with ball in hand. Munster are in the middle of changing their style from the Kidney style to a more expansive game. Even Connacht have been allowed to take the shackles off now that they're not simply the dumping ground for has-beens from the other provinces.
As the provincial/club game here has moved to a more expansive game it seems that the Ireland team has moved just as quickly in the opposite direction to a more conservative game plan. Deccie and the other Irish coaches are a big part of why Sexton looks a shadow of himself when he pulls on a green jersey.
Weather definitely has some effect on how adventurous a team's play might be, but no where near as much as a lack of ambition.