Climate - Portoroz (Slovenia)

The climate of Portoroz can be described as transitional Mediterranean.
Portorož (or Portorose) is located in the short coastal stretch of Slovenian, about 20 km (12 mi) south-west of Trieste. The sea mitigates the climate, but we are in the area where the bora can blow, the cold, dry wind from the eastern European plains.
Summer is hot and sunny, with the sea breeze, and a few rainy days.

Best Time

The best periods to visit Portoroz are spring and autumn, and in particular, from mid-April to mid-June and in the month of September. However, in both periods, some rainy days are possible.
The best months to go to the beach are July and August. In June, the sea is still a little cool.

Portoroz - Climate data

In Portoroz, the average temperature of the coldest month (January) is of 5.3 °C (41.5 °F), that of the warmest month (July) is of 23.4 °C (74.1 °F). Here are the average temperatures.
In Portoroz, precipitation amounts to 950 millimeters (37.4 inches) per year: so, it is at an intermediate level. It ranges from 50 mm (2 in) in the driest month (January) to 125 mm (4.9 in) in the wettest one (November). Here is the average precipitation.
At Portoroz, the sea temperature ranges from 10.5 °C (51 °F) in February to 25.5 °C (78 °F) in August. Here are the average sea temperatures.
In Portoroz, there are on average around 2415 sunshine hours per year. Here are the average hours of sunshine per day.

Portoroz - Weather by month

Based on the period 1991-2020

---

In January, the coldest month of the year, the weather in Portoroz is usually quite cold. The average temperature is of 5.3 °C (41 °F), with a minimum of 1.3 °C (34.4 °F) and a maximum of 9.2 °C (48.6 °F).
On the coldest nights of the month, the temperature usually drops to around -5 °C (23 °F). However, it dropped to -9.5 °C (14.9 °F) in January 2000.
On the warmest days of the month, the temperature usually reaches around 14.5 °C (58 °F). However, it reached 18.2 °C (64.8 °F) in January 2014.
Precipitation amounts to 50 mm (2 in), distributed over 6 days.
The day lasts on average 9 hours and 10 minutes.
There are on average 3.5 hours of sunshine per day. So, the sun shines 37% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average sea temperature is of 11.5 °C (53 °F). Therefore, the sea is very cold for swimming.

---

In February, the weather in Portoroz is usually quite cold. The average temperature is of 5.8 °C (42 °F), with a minimum of 1.2 °C (34.2 °F) and a maximum of 10.3 °C (50.6 °F).
On the coldest nights of the month, the temperature usually drops to around -4.5 °C (24.5 °F). However, it dropped to -10.3 °C (13.5 °F) in February 1991.
On the warmest days of the month, the temperature usually reaches around 15.5 °C (60 °F). However, it reached 19.2 °C (66.6 °F) in February 2006.
Precipitation amounts to 60 mm (2.4 in), distributed over 6 days.
The day lasts on average 10 hours and 25 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 45% of the time.
The average humidity is 75%. Hence, the air is normally humid.
The average sea temperature is of 10.5 °C (50.5 °F). Therefore, the sea is very cold for swimming.

---

In March, the weather in Portoroz is usually mild. The average temperature is of 9.1 °C (48 °F), with a minimum of 4.1 °C (39.3 °F) and a maximum of 14.1 °C (57.4 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -2 °C (28 °F). However, it dropped to -10.5 °C (13.1 °F) in March 2005.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 19.5 °C (67 °F). However, it reached 23.2 °C (73.8 °F) in March 2017.
Precipitation amounts to 55 mm (2.2 in), distributed over 6 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 50% of the time.
The average humidity is 70%.
The average sea temperature is of 11 °C (52 °F). Therefore, the sea is very cold for swimming.

---

In April, the weather in Portoroz is usually mild. The average temperature is of 12.9 °C (55 °F), with a minimum of 7.6 °C (45.7 °F) and a maximum of 18.1 °C (64.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 1.5 °C (34.5 °F). However, it dropped to -4.2 °C (24.4 °F) in April 2003.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 24 °C (75.5 °F). However, it reached 28.2 °C (82.8 °F) in April 2018.
Precipitation amounts to 65 mm (2.6 in), distributed over 8 days.
The day lasts on average 13 hours and 35 minutes.
There are on average 7 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 70%.
The average sea temperature is of 13.5 °C (56.5 °F). Therefore, the sea is very cold for swimming.

---

In May, the weather in Portoroz is usually very mild. The average temperature is of 17.2 °C (63 °F), with a minimum of 11.8 °C (53.2 °F) and a maximum of 22.7 °C (72.9 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 6.5 °C (43.5 °F). However, it dropped to 3.3 °C (37.9 °F) in May 2011.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 28 °C (83 °F). However, it reached 33.2 °C (91.8 °F) in May 2008.
Precipitation amounts to 75 mm (3 in), distributed over 8 days.
The day lasts on average 14 hours and 55 minutes. So the days are long.
There are on average 8.5 hours of sunshine per day. So, the sun shines 57% of the time.
The average humidity is 70%.
The average sea temperature is of 18 °C (64.5 °F). Therefore, the sea is cold for swimming.

---

In June, the weather in Portoroz is usually warm. The average temperature is of 21.3 °C (70 °F), with a minimum of 15.5 °C (59.9 °F) and a maximum of 27 °C (80.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 10.5 °C (50.5 °F). However, it dropped to 6.4 °C (43.5 °F) in June 2006.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 32.5 °C (90 °F). However, it reached 35.6 °C (96.1 °F) in June 2019.
Precipitation amounts to 75 mm (3 in), distributed over 6 days.
The day lasts on average 15 hours and 35 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 9.5 hours of sunshine per day. So, the sun shines 62% of the time.
The average humidity is 70%.
The average sea temperature is of 22.5 °C (72.5 °F). Therefore, the sea can be considered barely acceptable for swimming.

---

In July, the warmest month of the year, the weather in Portoroz is usually warm to hot. The average temperature is of 23.4 °C (74 °F), with a minimum of 17.4 °C (63.2 °F) and a maximum of 29.4 °C (85 °F).
On the coldest nights of the month, the temperature usually drops to around 12.5 °C (54 °F). However, it dropped to 8.8 °C (47.8 °F) in July 2007.
On the warmest days of the month, the temperature usually reaches around 34 °C (93.5 °F). However, it reached 37.4 °C (99.3 °F) in July 2015.
Precipitation amounts to 60 mm (2.4 in), distributed over 5 days.
The day lasts on average 15 hours and 10 minutes. So the days are long.
There are on average 11 hours of sunshine per day. So, the sun shines 71% of the time.
The average humidity is 65%.
The average sea temperature is of 25 °C (77 °F). Therefore, the sea is warm enough for swimming.

---

In August, the weather in Portoroz is usually warm to hot. The average temperature is of 23.4 °C (74 °F), with a minimum of 17.3 °C (63.1 °F) and a maximum of 29.5 °C (85 °F).
On the coldest nights of the month, the temperature usually drops to around 11.5 °C (53 °F). However, it dropped to 7.5 °C (45.5 °F) in August 2005.
On the warmest days of the month, the temperature usually reaches around 33.5 °C (92.5 °F). However, it reached 37.3 °C (99.1 °F) in August 2017.
Precipitation amounts to 70 mm (2.8 in), distributed over 6 days.
The day lasts on average 14 hours and 0 minutes.
There are on average 10 hours of sunshine per day. So, the sun shines 72% of the time.
The average humidity is 70%.
The average sea temperature is of 25.5 °C (78 °F). Therefore, the sea is warm enough for swimming.

---

In September, the weather in Portoroz is usually warm. The average temperature is of 19.1 °C (66 °F), with a minimum of 13.7 °C (56.6 °F) and a maximum of 24.6 °C (76.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 8 °C (46.5 °F). However, it dropped to 4.8 °C (40.6 °F) in September 2008.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 29.5 °C (84.5 °F). However, it reached 32.5 °C (90.5 °F) in September 2016.
Precipitation amounts to 120 mm (4.7 in), distributed over 8 days.
The day lasts on average 12 hours and 30 minutes.
There are on average 7.5 hours of sunshine per day. So, the sun shines 59% of the time.
The average humidity is 75%. Hence, the air is normally humid.
The average sea temperature is of 23 °C (73.5 °F). Therefore, the sea can be considered barely acceptable for swimming.

---

In October, the weather in Portoroz is usually very mild. The average temperature is of 14.9 °C (59 °F), with a minimum of 10.2 °C (50.3 °F) and a maximum of 19.6 °C (67.3 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 3 °C (37 °F). However, it dropped to -1.8 °C (28.8 °F) in October 2003.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 24.5 °C (76 °F). However, it reached 27.5 °C (81.5 °F) in October 2000.
Precipitation amounts to 105 mm (4.1 in), distributed over 8 days.
The day lasts on average 10 hours and 55 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 49% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average sea temperature is of 19.5 °C (67.5 °F). Therefore, the sea is very cool for swimming.

---

In November, the weather in Portoroz is usually mild. The average temperature is of 10.5 °C (51 °F), with a minimum of 6.6 °C (43.8 °F) and a maximum of 14.5 °C (58 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -1 °C (30 °F). However, it dropped to -5 °C (23 °F) in November 1995.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 20 °C (68.5 °F). However, it reached 24.4 °C (75.9 °F) in November 2004.
Precipitation amounts to 125 mm (4.9 in), distributed over 9 days.
The day lasts on average 9 hours and 30 minutes.
There are on average 3 hours of sunshine per day. So, the sun shines 34% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average sea temperature is of 16.5 °C (61.5 °F). Therefore, the sea is cold for swimming.

---

In December, the weather in Portoroz is usually quite cold. The average temperature is of 6.4 °C (43 °F), with a minimum of 2.4 °C (36.3 °F) and a maximum of 10.3 °C (50.6 °F).
On the coldest nights of the month, the temperature usually drops to around -4.5 °C (24 °F). However, it dropped to -9.9 °C (14.2 °F) in December 2009.
On the warmest days of the month, the temperature usually reaches around 15.5 °C (60 °F). However, it reached 19.1 °C (66.4 °F) in December 2014.
Precipitation amounts to 80 mm (3.1 in), distributed over 7 days.
The day lasts on average 8 hours and 50 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 3 hours of sunshine per day. So, the sun shines 35% of the time.
The average humidity is 80%. Hence, the air is normally humid.
The average sea temperature is of 14 °C (57 °F). Therefore, the sea is very cold for swimming.