An "act of God" is defined as "a natural catastrophe which no one can prevent such as an earthquake, a tidal wave, a volcanic eruption, a hurricane or a tornado. An act of God is generally considered an act attributable to nature without human interference. Acts of God have legal significance because "acts of God" are a legal excuse for delay or failure to fulfill an obligation or to complete a construction project."
A modification to the contract using the Changes clause is appropriate if the government directs the contractor to perform the new work resulting from the hurricane damage, i.e., clean-up, site restoration since the damage was outside the control of the contractor.
The above response is based solely on the question and background information provided. As we do not have all facts particular to your contract, program, and situation, we highly recommend you consult your contracting officer and legal office for guidance.