The North Sea mitigates temperatures. Although temperatures of the North Sea differ a lot depending the area. Around the Shetland islands in the far north water temperatures are year round ca. 10 degrees Celsius. More towards the Continent temperatures vary more. At the south coast, the North Sea is at its coldest in February with an average temperature of ca. 5 degrees Celsius and at its hottest in August with an average temperature of ca. 17 degrees Celsius. The water of the Wadden Sea varies more again. This has to do with the swallow water and it therefore warms up and cools down quickly. During the coldest month February the Wadden Sea in Germany can be as cold as -1,5 degrees Celsius and during the warmest month in August even up to 23 degrees Celsius.
So, when you're on one of the ca. 50 Wadden Sea islands it can make a difference if you go swimming at the North Sea side or at the Wadden Sea side.
It will be no surprise but it's a sea climate and temperatures are moderate with a North Sea mitigating temperatures along the coasts.
Temperatures along the North Sea coast of Belgium and the Netherlands (between 't Zwin in Flanders and province Noord Holland), what's more-or-less former West Frisia, are the lowest in January/February with an average daytime temperature of ca. 6 or 7 degrees Celsius and highest in July/August with ca. 22 or 23 degrees Celsius.
Average daytime temperatures along the Wadden Sea coasts of southwest Denmark, northwest Germany and in the north of the Netherlands are at its coldest in January/February with a daytime average of ca. 5 degrees Celsius and at its hottest in July/August with a daytime average of ca. 22 degrees Celsius. Not much difference along the whole Wadden Sea coast, maybe 1 degree lower on average in North Frisia (i.e. Landkreis Nordfriesland) in Germany compared to Mid Frisia (i.e. province Friesland and the region of the Ommelanden in province Groningen) in the Netherlands.
With this climate no worries for harsh winters. If in the exceptional situation temperatures do drop enormously low and you happen to be hiking, forget walking. Buy skates and start ice-skating. Everyone else does too. It will be a unique experience seeing everyone skating on canals and on rivers. If things really get cold the Elfstedentocht 'eleven cities tour' will be skated in the province Friesland. Millions of people will watch this event globally and you will not be able to find any accommodation anymore in the province. It is a complete lock down. Don't be afraid though, the last Elfstedentocht took place in 1997.
Winds, especially during the months December and January, can be very strong at the coast with the dunes, terps (also called a wierde, Warft or Wurt, etc.) and dykes of the Frisia coast being their first (low) obstacle. The direction of the wind is prevailing southwest or west, especially during autumn, winter and early spring. Typically low-pressure systems will enter from the Atlantic Ocean during this period. Winter and spring are also typically the months for storms, floods and great floods. So this is the time the salt marshes of the Wadden Sea and of the Halligs are submerged by the sea regularly and the clay is so wet you sink to your knies into it. Un-doable and dangerous.
Hiking through the tidal marshlands is extremely difficult and potentially risky. The great floods in history mostly have taken place during these dark months, read also our blog post Half a million deaths. A forgotten North Sea disaster... In summer high-pressure systems gain influence above the European continent and wind directions coming regular from the south and from the east serving warmer temperatures on your (tidal) plate.
Always be prepared for rain and do not economize on rain gear on this trail. That means carry your Friesennerz 'oil-skin jacket' with you at all times. Low-pressure systems coming in from the Atlantic shake off a lot of rain already above the British Isles, but not all of it. In the Netherlands the wettest month is August with an average of ca. 180 mm rain. The driest month is February with an average of ca. 45 mm rain. Feels counter intuitive, right? For East Frisia (i.e. the region of Ostfriesland) in Germany it rains on average 16/17 days a month, with the wettest months between November and January .
Letting the statistics above sink in (namely, it rarely freezes and the lowest precipitation is during winter with a lot of rain) you understand why hoping for a white Christmas is really a silly thing to do for the coastal-zone people. It happened only eleven times in the last century. Therefore, hiking in winter will not confront you normally with (a lot of) snow. If it falls, it will present you no challenge to plough through it.
But, but, but. The beautiful thing of the sea climate in combination with a flat land, are the clouds, the changing light and the low skies. It can be truly amazing, especially when the weather is rough and not traditional 'nice'. The so-called low sky is truly part of the this coastal landscape.
Do hike under the clouds!
Note 1 – With all this damp weather, salty sea winds and (former) peat lands, we do not understand why whisky distilleries have not become a big hit.
Note 2 – Featured image, Wadden Sea island Ameland by Hans Faber.
The Cult, Rain (1985)
Jimi Hendrix, Rainy Day, Dream Away (1968)