Climate and monthly weather forecast
Hanko, Finland

Lying within the Köppen climate zone Dfb, Hanko experiences a humid continental climate. This climate classification is defined by no dry season and a warm summer. Hanko's geographical position on the south coast of Finland exposes it to weather conditions heavily influenced by its proximity to the sea.

The climate in Hanko goes through significant variations all through the year. An analysis of climatological data reveals that the average sea temperature ranges from 0.3°C (32.5°F) in February to 17.8°C (64°F) in August. Similarly, daylight hours stretch from a mere 6.1 hours in December to as long as 18.7 hours in June.

Hanko's weather patterns uniquely express themselves with prominent fluctuations not only between seasons but also within each season. While the town lacks any extremely hot or cold months, its maritime location amplifies the humidity during winter and summer, providing a relatively moderate climate compared to other inland locations in Finland.

Considering the varying climatic conditions, the best time to visit Hanko would be between June and August. During this period, the town experiences the longest daylight hours, averaging between 17.9 to 18.7 hours, and the warmest sea temperatures, from 16.9°C (62.4°F) to 17.8°C (64°F). These conditions make the summer months ideal for outdoor activities and water sports.

Contrastingly, the least favourable time to visit Hanko falls between December and February. The town undergoes the shortest daylight hours, ranging from 6.1 to 9.2 hours, during this period. Simultaneously, the sea temperatures plunge to their lowest, from 0.3°C (32.5°F) to 1.8°C (35.2°F), making it quite challenging for outdoor activities and water-based recreation.

Spring in Hanko, observed from March to May, signals a gradual transition from the cold winter. Sea temperatures begin to rise from 1.7°C (35.1°F) in March to 5.8°C (42.4°F) in May. The increase in daylight hours, from 11.8 to 17.2 hours, towards the end of spring suggests an onset of more friendly weather conditions.

Summer in Hanko, lasting from June to August, presents the warmest conditions of the year. The sea temperature peaks at 17.8°C (64°F) in August while daylight hours persist for about 17.9 to 18.7 hours. These conditions provide bountiful opportunities for tourism and water-based activities.

Autumn in Hanko descends between September and November. The change from summer to autumn is marked by a drop in sea temperatures from 14.9°C (58.8°F) in September to 7.3°C (45.1°F) in November. Daylight hours also decrease significantly, from 12.9 hours to 7.6 hours, in the same span.

Winter season in Hanko, spanning from December to February, shows distinct yet moderate climatic conditions due to the maritime influence. Daylight hours are at their shortest, fluctuating from 6.1 to 9.2 hours, and sea temperatures dance near freezing levels from 0.3°C (32.5°F) to 1.8°C (35.2°F). While Hanko experiences rather mild winters as per Finnish standards, outdoor activities could still be curtailed due to these conditions.

In comparison to the preceding month of December, January in Hanko, Finland experiences intensifying severity in cold weather. Residents prepare for an average sea temperature of about 1.8°C (35.2°F). Despite the submerged thermometer readings, the daylight hours start to increase, signaling the far-off spring. Weather in January »

February's weather in Hanko still carries on from January's intense cold, albeit with a slightly warmer sea temperature. The recorded sea temperature averages around 0.4°C (32.7°F) in this month. Characteristically, February is a month of extended daylight but remains within winter's tight grip. Weather in February »

In Hanko, March experiences a gradual shift from the harsher winter months. The sea begins to marginally thaw with a recorded average temperature of about 0.3°C (32.5°F). The residents' anticipation for the coming spring can be seen as daylight hours extend further. Weather in March »

April's weather in Hanko communicates the valiant return of spring. The thawing process accelerates in the sea, with an average temperature climbing to approximately 1.7°C (35.1°F). An increase in daylight hours hints at prolonged periods of sunlight, lighting up the city for longer stretches. Weather in April »

May heralds the definite arrival of spring in Hanko. The sea temperature shows a dramatic jump, averaging around 5.8°C (42.4°F) that contributes to an agreeable climate. Charming daylight hours metamorphose the city into a vivid canvas of color and activity. Weather in May »

June showcases the beginning of summer in all its glory in Hanko. The sea becomes inviting with an average temperature of a pleasant 12.3°C (54.1°F). Lengthy daylight hours make outdoor activities a delight, with citizens making the most out of vibrant sunny afternoons. Weather in June »

July is the high point of summer in Hanko, with the city immersed in pleasant warmth. The sea temperature soars to a peak, averaging about 16.9°C (62.4°F), perfect for beachgoers. July's bountiful daylight allows for extended outdoor entertainment and relaxation. Weather in July »

The city of Hanko continues to bask in summer warmth throughout August. A mild dip in sea temperature is noticed, with an average around 17.8°C (64°F). The diminishing daylight hours subtly hint at the impending end of summertime, invoking a sense of melancholy. Weather in August »

September witnesses a crisp transition from warm summer to cooler autumn in Hanko. The average sea temperature plunges to around 14.9°C (58.8°F) indicating the onset of fall. The shrinking daylight hours are a gentle reminder of the approaching colder months. Weather in September »

October presents a significant dip in temperature marking a pronounced transition to cooler months in Hanko. A dramatic drop in sea temperature, averaging about 10.4°C (50.7°F), signals the onset of chillier days. The dwindling daylight hours add a captivating melancholic charm to the city. Weather in October »

November marks the onset of winter in Hanko, characterized by colder temperatures and shorter days. The average sea temperature dips to about 7.3°C (45.1°F). Daylight becomes scarce as the sun skims the horizon for shortened intervals. Weather in November »

December welcomes a freezing winter in full force in Hanko. The city is hurled into sub-zero conditions with sea temperatures averaging around 4.3°C (39.7°F). The limited daylight confines most of the city's activity indoors, inducing a sense of hibernation. Weather in December »