Yes you can!
The miniULTRA chiller has a IPX6 Water Resistance Rating, which is ideal for outdoor use.
But for your own safety and the safety of others, ensure the chiller is plugged into an AC socket or extension cable that is suitable for use, properly grounded, has a built in surge protector and preferably is IP65 rated. For your safety, the chiller must also be switched off when you start your cold water therapy session.
Although the chiller is tested to a IPX6 water resistance rating, it is still advisable that the chiller is kept dry at all times, do not immerse, splash or spray the unit with water.