As a contractor we plan a schedule and base line it. We all know we have contingency reserves, we have management reserves and we have project reserves. Were do we cover the act of god impacts. How can we asses the act of god impact on starting stage of the project. For example in middle east 3-4 months heat index and sudden rains Saving Changes...
Contracts would often have a force majeure section or clause covering major issues which are out of the team's control. Otherwise, if it is something which can be proactively identified as a risk (the Middle East heat or rains example), then contingency reserves and schedule buffers should cover that.