According to Croatian Meteorological and Hydrological Service there is no danger of a cold wave in Dubrovnik Neretva County until January 5th, while on January 6 a very high risk of a cold wave is expected.
Read the recommendations on protecting the health from low temperatures:
Avoid early morning or nighttime exit
Do not go out without a cap, scarves and gloves
Do not stay outdoor for a long period of time
Take enough amount of hot drinks – tea, soup, up to two cups of coffee a day – limit the intake of alcohol
Keep track of the temperature in the room you are in (thermometer / thermostat)
Frequently contact the elderly and those who live alone