Winter time vacation (Prius left in the cold)

The main issue is that the 12V battery probably will be dead after one month, if it is not in perfect condition and fully-charged prior to your trip.

 

On a Gen2 the Smart Key System (SKS) can discharge the 12v on standing.
There is a button under the steering column to turn off the SKS system, which I use for 1-week or two down times.
Don't know what I'd do for a month, but some would disconnect battery or use a trickle charger.

The other thing I seem to notice after standing one week, is my HV battery goes into purple right away, espically if air cond is on. In the future, I am going to try to remember to let the car idle to warm up after a long down period, before I drive off.

 

Will it be inside or outside during these periods of non-use ?

Either way, having both batteries near to full charge when parked will help.

If it's inside, a ~$25 battery tender will ensure the 12 V is cared for and the traction battery should be fine without any special attention.

 

IF.....the battery is fully charged when you park it, it should be OK for 2 weeks.
That should be a good test though.