You need to remember that the weather in Tatra Mountains can change dramatically within a period of few hours, and in general the higher you climb, the colder it gets.
From spring till autumn (summer included) you may frequently experience low temperatures, rain, strong wind, thunderstorms, hailstone and sleet.
In winter, snow, ice and avalanches are common.
The sun is very intense at higher altitudes and UV exposure is higher in mountains comparing to the valleys. You can still get sunburned in winter!
What to bring
If in any doubt about what else to bring, please contact me via e-mail. Also, there are plenty of professional outdoor clothing shops in town of Zakopane so don't worry if you forget something.
In Poland, Polish Zloty is the official currency. In Slovakia you can use Euros. There are plenty of currency exchange shops and ATM machines available for you in Zakopane.