For how long does Google honor a 302 redirect?

[g-s-m]

Greetings!  I would love some recent experiences to support our experience which is +/- 1 year old on this question.

Based on our experiences around a year ago, I believe that Google will only honor a 302 temporary redirect for a relatively short period - perhaps up to a month - and then it will begin treating the redirect as a 301 redirect and will remove the old page from the index.  Have others seen this?  Is there an update on what the max "safe" period to have a 302 in place could be?

We have a domain that is soon to experience about 3 months of "downtime" with no content on it, but the content will be back after that time.  Ideally we would 302 redirect the pages elsewhere just for that downtime period.  However, I don't want to do a 302 redirect if there is a risk that the pages will lose all of their accumulated authority and indexing.  Basically, is there any safe way to just put the domain on ice for a few months?

Please share recent experience only. Thanks for your insights!

[TomRayner]

While I can't help with the second part of your question just now, I can help with the first.  There have been a couple of studies that have argued that 302 redirects are eventually treated as 301s.  Here is one example.