There's always going to be some loss in your high-end strength during such a long layoff, but your hope should be that the muscle memory paradigm is true and you'll be able to regain this strength within a matter of a few weeks, provided you are consistent and eat well.
I don't like being out of town for very long for the sole reason that my routine gets screwed up, so when you travel for longer periods of time, try as best as you can to emulate the normal routine that you have at home (i.e., same diet, same activities if possible). If you have no access to weights, at the very least do some bodyweight circuits at a higher intensity and focus on training your conditioning and endurance during the layoff. Bring resistance bands with you, they help out a lot.
I also like to consume several grams of BCAAs spread out throughout the day when I'm on vacation or have time off training. Not sure if this actually helps prevent losing too much muscle, but it can't hurt.