Power outage, excessive heat, ... unpredictables, do you refund?

[Kevin Lefeuvre]

We are experiencing heat wave right now in LA (and other areas in the state and in the country), where the A/Cs are not totally efficient. Some areas have even experienced power outage during the most part of the week-end.

How do you handle situations where the host is not responsible for the issues but at the end, the guest's experience is far from being good. 

Do you partially refund?

[Michael Greenberg]

I like @John Underwood's comment, discount on their next stay.  I think this falls under the "Acts of God" clause since it is out of your control and I would think guests would understand this.  The other option would be to notify them ahead of their arrival that this might occur and the reasoning for it.  This would be my strategy to be "above board" with my guests.