I think the short answer is: we don't know (yet).
Let me explain why we should stick with this answer until we get the 'accepted answer' from historians.
First, and most obviously, we are speculating and attempting to do historiography as we progress through the list of battles, separating them into whether it rained or not, then check the results of the battles. I'm not sure this would qualify as historical research.
Second, this question is clearly under MilGeo, "Military Geography" (Wikipedia). But, and a BIG but, this is not a well-established topic in the study of history. It can ill-afford weak historical research if it is to get traction with the general population (nor help with the credibility of this site). Hence, even if inadvertently, we will do this area of historical study more harm than good if we were to speculate.
Not a well-established topic: For instance, the Wikipedia link, under section on History and Development of Military Geography, lists a single book to 20th century (1938). In fact, there has been earlier texts from 19th century, such as, T. Miller Macguire's 'Outlines of Military Geography (Cambridge, 1898)' and George Lund Dunnet's 'The Military Geography by an Army Schoolmaster' (Gale & Polden, Brompton Works, Chatham, 1889).
Finally -- on why we should continue to be patient -- since 1994, there has been regular symposiums/conferences all over the world by International Association of Military Geoscientists (this site is hosted by US Navy). Each symposium has a specific theme and, where historical battles are involved, historians do participate. For instance, the one from 2000 (Theme: International Terrain in Military History) resulted in 'Fields of Battle: Terrain in Military History' (Springer, 2002). It did cover some medieval battles, but unfortunately not the Hundred Years' War (the location focus was mainly on the British Isles).
Let me end with a hopeful quote from the editors of Fields of Battle (p.1) (emphasis mine):
Clearly, once a battle is entered into, then all aspects of the terrain may be employee! by astute commanders, and many examples exist where geology, geomorphology or meteorology have combined to defeat an attacker or help a defender. Despite the widespread recognition of the importance of terrain within military action, it has rarely been used as an historical tool to help deconstruct events, actions and outcomes of military engagements, yet clearly its potential to impact our understanding of such actions is considerable. In recent years, however, the relevance of terrain as a tool in the analysis of historical engagements has gained some momentum and it is hoped that this volume will continue this trend.