Climate - Postojna (Slovenia)

The climate of Postojna is moderately continental, with cold winters and warm summers.
The city is located in the Karst hills, at 530 meters (1,700 feet) above sea level, and 30 km (18 mi) north-east of Trieste.
Precipitation is abundant, and in winter there can be heavy snowfalls.
In winter, the bora, the cold wind from the plains of Eastern Europe, can blow. During cold spells, the temperature can drop to -20 °C (-4 °F) or even below. The cold record is -26.4 °C (-15.5 °F), set in January 1968.
In summer, temperatures are pleasant and are suitable for outdoor activities, although there can be rains and thunderstorms, even strong.
Sometimes there can be hot periods, although less so than in the plains. The heat record is 36.4 °C (97.5 °F), set in August 2013.

Best Time

The best time to visit Postojna runs from mid-May to mid-September, since it is the warmest and sunniest period of the year. Sometimes, it can be hot in July and August, while in other circumstances, nights can be cool or even a little cold even in these months, so it can be useful to bring a sweatshirt or sweater and a light jacket for the evening.

Postojna - Climate data

In Postojna, the average temperature of the coldest month (January) is of 0.7 °C (33.2 °F), that of the warmest month (August) is of 19.6 °C (67.2 °F). Here are the average temperatures.
In Postojna, precipitation amounts to 1525 millimeters (60 inches) per year: it is therefore abundant. It ranges from 90 mm (3.5 in) in the driest month (January) to 185 mm (7.3 in) in the wettest one (November). Here is the average precipitation.
In Postojna, there are on average around 2000 sunshine hours per year. Here are the average hours of sunshine per day.

Postojna - Weather by month

Based on the period 1991-2020

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In January, the coldest month of the year, the weather in Postojna is usually cold. The average temperature is of 0.7 °C (33 °F), with a minimum of -2.8 °C (27 °F) and a maximum of 4.1 °C (39.4 °F).
On the coldest nights of the month, the temperature usually drops to around -11 °C (12.5 °F). However, it dropped to -16.8 °C (1.8 °F) in January 2000.
On the warmest days of the month, the temperature usually reaches around 11.5 °C (52.5 °F). However, it reached 15.3 °C (59.5 °F) in January 2013.
Precipitation amounts to 90 mm (3.5 in), distributed over 8 days.
The day lasts on average 9 hours and 5 minutes.
There are on average 3 hours of sunshine per day. So, the sun shines 33% of the time.
The average humidity is 83%. Hence, the air is normally humid.

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In February, the weather in Postojna is usually cold. The average temperature is of 1.7 °C (35 °F), with a minimum of -2.6 °C (27.3 °F) and a maximum of 6.1 °C (42.9 °F).
On the coldest nights of the month, the temperature usually drops to around -10.5 °C (13 °F). However, it dropped to -15.5 °C (4.1 °F) in February 2018.
On the warmest days of the month, the temperature usually reaches around 13.5 °C (56.5 °F). However, it reached 21 °C (69.8 °F) in February 1998.
Precipitation amounts to 105 mm (4.1 in), distributed over 8 days.
The day lasts on average 10 hours and 25 minutes.
There are on average 4 hours of sunshine per day. So, the sun shines 39% of the time.
The average humidity is 80%. Hence, the air is normally humid.

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In March, the weather in Postojna is usually quite cold. The average temperature is of 5.4 °C (42 °F), with a minimum of 0.4 °C (32.7 °F) and a maximum of 10.3 °C (50.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -7 °C (19 °F). However, it dropped to -19.5 °C (-3.1 °F) in March 2005.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 18 °C (64 °F). However, it reached 22.2 °C (72 °F) in March 2019.
Precipitation amounts to 100 mm (3.9 in), distributed over 8 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 42% of the time.
The average humidity is 78%. Hence, the air is normally humid.

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In April, the weather in Postojna is usually mild. The average temperature is of 9.2 °C (49 °F), with a minimum of 3.7 °C (38.6 °F) and a maximum of 14.7 °C (58.5 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -3 °C (26.5 °F). However, it dropped to -9.2 °C (15.4 °F) in April 2003.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 22 °C (71.5 °F). However, it reached 27.9 °C (82.2 °F) in April 2012.
Precipitation amounts to 115 mm (4.5 in), distributed over 11 days.
The day lasts on average 13 hours and 35 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 43% of the time.
The average humidity is 77%. Hence, the air is normally humid.

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In May, the weather in Postojna is usually mild. The average temperature is of 13.6 °C (57 °F), with a minimum of 7.7 °C (45.9 °F) and a maximum of 19.5 °C (67.1 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 1.5 °C (35 °F). However, it dropped to -1.7 °C (28.9 °F) in May 2019.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 26.5 °C (79.5 °F). However, it reached 31.6 °C (88.9 °F) in May 2009.
Precipitation amounts to 130 mm (5.1 in), distributed over 11 days.
The day lasts on average 15 hours and 0 minutes. So the days are long.
There are on average 7 hours of sunshine per day. So, the sun shines 45% of the time.
The average humidity is 77%. Hence, the air is normally humid.

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In June, the weather in Postojna is usually very mild. The average temperature is of 17.5 °C (63 °F), with a minimum of 11.4 °C (52.5 °F) and a maximum of 23.6 °C (74.4 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 6 °C (42.5 °F). However, it dropped to 1.6 °C (34.9 °F) in June 1994.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 30 °C (86 °F). However, it reached 34.6 °C (94.3 °F) in June 2019.
Precipitation amounts to 120 mm (4.7 in), distributed over 10 days.
The day lasts on average 15 hours and 40 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 7.5 hours of sunshine per day. So, the sun shines 49% of the time.
The average humidity is 79%. Hence, the air is normally humid.

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In July, the weather in Postojna is usually warm. The average temperature is of 19.5 °C (67 °F), with a minimum of 13 °C (55.4 °F) and a maximum of 26 °C (78.8 °F).
On the coldest nights of the month, the temperature usually drops to around 7.5 °C (45.5 °F). However, it dropped to 3.6 °C (38.5 °F) in July 1993.
On the warmest days of the month, the temperature usually reaches around 31.5 °C (89 °F). However, it reached 35 °C (95 °F) in July 2006.
Precipitation amounts to 100 mm (3.9 in), distributed over 8 days.
The day lasts on average 15 hours and 20 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 77%. Hence, the air is normally humid.

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In August, the warmest month of the year, the weather in Postojna is usually warm. However, there are remarkable differences between night and day. The average temperature is of 19.6 °C (67 °F), with a minimum of 13 °C (55.4 °F) and a maximum of 26.1 °C (79 °F).
On the coldest nights of the month, the temperature usually drops to around 6.5 °C (44 °F). However, it dropped to 3 °C (37.4 °F) in August 1995.
On the warmest days of the month, the temperature usually reaches around 31.5 °C (88.5 °F). However, it reached 36.4 °C (97.5 °F) in August 2013.
Precipitation amounts to 110 mm (4.3 in), distributed over 8 days.
The day lasts on average 14 hours and 0 minutes.
There are on average 8.5 hours of sunshine per day. So, the sun shines 61% of the time.
The average humidity is 79%. Hence, the air is normally humid.

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In September, the weather in Postojna is usually very mild. The average temperature is of 15.0 °C (59 °F), with a minimum of 9.6 °C (49.3 °F) and a maximum of 20.3 °C (68.6 °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 -2 °C (28.4 °F) in September 1995.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 26 °C (79 °F). However, it reached 31.2 °C (88.2 °F) in September 2011.
Precipitation amounts to 160 mm (6.3 in), distributed over 10 days.
The day lasts on average 12 hours and 30 minutes.
There are on average 6 hours of sunshine per day. So, the sun shines 49% of the time.
The average humidity is 82%. Hence, the air is normally humid.

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In October, the weather in Postojna is usually mild. The average temperature is of 10.7 °C (51 °F), with a minimum of 6.5 °C (43.7 °F) and a maximum of 15 °C (59 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -2 °C (28.5 °F). However, it dropped to -9.6 °C (14.7 °F) in October 2003.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 21.5 °C (70.5 °F). However, it reached 25.9 °C (78.6 °F) in October 2017.
Precipitation amounts to 165 mm (6.5 in), distributed over 11 days.
The day lasts on average 10 hours and 55 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 40% of the time.
The average humidity is 83%. Hence, the air is normally humid.

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In November, the weather in Postojna is usually quite cold. The average temperature is of 6.1 °C (43 °F), with a minimum of 2.7 °C (36.8 °F) and a maximum of 9.4 °C (49 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -6.5 °C (20 °F). However, it dropped to -15.6 °C (3.9 °F) in November 1999.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 16.5 °C (61.5 °F). However, it reached 21.8 °C (71.2 °F) in November 2015.
Precipitation amounts to 185 mm (7.3 in), distributed over 12 days.
The day lasts on average 9 hours and 30 minutes.
There are on average 2.5 hours of sunshine per day. So, the sun shines 28% of the time.
The average humidity is 84%. Hence, the air is normally humid.

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In December, the weather in Postojna is usually cold. The average temperature is of 1.4 °C (35 °F), with a minimum of -2 °C (28.3 °F) and a maximum of 4.9 °C (40.9 °F).
On the coldest nights of the month, the temperature usually drops to around -11.5 °C (11.5 °F). However, it dropped to -19 °C (-2.2 °F) in December 2010.
On the warmest days of the month, the temperature usually reaches around 12 °C (53 °F). However, it reached 15.5 °C (59.9 °F) in December 2016.
Precipitation amounts to 140 mm (5.5 in), distributed over 10 days.
The day lasts on average 8 hours and 40 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 2.5 hours of sunshine per day. So, the sun shines 30% of the time.
The average humidity is 84%. Hence, the air is normally humid.