The highest day temperature in May 2026 was 85°F. The lowest night temperature was 35°F. The average values for day and night temperatures during May were 68.2°F и 51.6°F respectivly.

The average sea surface temperature in May 2026 for Opatija was 63.7°F. The maximum and minimum values were 59.6°F and 70.6°F respectively.

Most of the days in May are sunny but you can also expect cloudy and gloomy days.

Precipitation total in May for Opatija is 3.7 in. It makes may one of the most rainy months of the year.

The average wind speed in May is 6.3 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Opatija in May is 9.2 hours.