August in northern Poland. Heat returns, violent storms and a solar eclipse over the water

July ended in a heatwave, August opened with thunderstorms and a short reprieve. That was only the prelude: another surge of hot air is advancing from the south, and mid-month brings a deep partial solar eclipse. What follows is the outlook for the coming weeks across West, Central and East Pomerania, Warmia-Masuria and Kuyavia-Pomerania, based on the analysis by Damian Zbieg of Meteo24.com.pl, a meteorologist working with Gazeta Morska.

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03 august 2026   |   12:30   |   Source: Gazeta Morska   |   Prepared by: Kamil Kusier   |   Print

fot. Mariusz Jasłowski

How the month began

The first day of August brought a system of atmospheric fronts across Poland. Along an undulating zone of violent thunderstorms and large-scale precipitation, it separated tropical air from the milder polar maritime air flowing in from north-western Europe. A day later a high-pressure system reached the country, pushing the front beyond the eastern and southern borders.

In the north and on the coast that meant temperatures of 20 to 22 degrees, moderate by midsummer standards.

- A high-pressure system reached the country, pushing the front beyond the eastern and southern borders. Conditions will favour time spent at the sea, at lakes and on smaller inland waters, says Damian Zbieg.

The meteorologist points out that on the coast this situation plays out differently than inland.

- A high over Poland means weak pressure gradients, and with a weak gradient it is no longer the synoptic situation that governs the wind at sea but the temperature difference between land and water. Hence the calm mornings and a wind that only wakes up during the day, Zbieg explains.

The week ahead: hot air from the south and the return of storms

The most significant change concerns the week now beginning. A surge of hot air is advancing from the south, and nationally maximum temperatures may again reach 30 to as much as 39 degrees. In exchange, violent thunderstorms return.

For this region, though, something other than the peak figures matters.

- The greatest heat will build in the south and south-east, while the north stays somewhat milder. That is a typical pattern for tropical air arriving from the south: before it reaches the Baltic it loses part of its energy, and the sea itself cools it further, says Damian Zbieg.

In practice Pomerania and Warmia usually run several degrees cooler than the interior, and the difference tends to be greatest in the narrow coastal belt. That does not mean calmer weather. It is precisely along the boundary between hot air over land and cooler air over the Baltic that the most dynamic storm systems form, and in August that boundary can stall directly over the coast.

Storms in this configuration rarely build gradually. They develop fast and produce strong gusts along the outflow boundary, and over water, where surface friction is absent, wind speeds run higher than on the adjacent land. That is the single most important point for anyone planning to go afloat this week, and it applies as much to the Masurian lakes as to the Baltic.

The weekend of 7-9 August: a mild cooldown from the north-west

For the coming weekend the forecast indicates a further, relatively mild cooldown within the same synoptic cycle.

- Another relatively mild cooldown is possible within this synoptic cycle, as air from the north-western sector replaces the hot tropical airmass, Zbieg forecasts. - At sea such changes usually mean stronger winds, because a flow from that sector is simply more dynamic than a stagnant tropical airmass.

For this region the north-westerly flow registers more than the temperature change itself. Offshore it means a more pronounced sea state, and on the western stretches of coast different approach conditions for harbours. Baltic seas build quickly and decay slowly, so unsettled water can persist for a day after the front has passed.

Wednesday 12 August: heat returns, and an eclipse

The most anticipated day of the month falls on Wednesday 12 August.

- Very preliminary calculations for Wednesday 12 August suggest a return of the heat, so clearer skies are the likelier outcome, allowing observation of a spectacular eclipse of the setting sun, says Damian Zbieg. - With timing like that, low cloud and visibility right at the horizon will be decisive, and that is precisely the element which cannot be predicted this far ahead. It is worth checking the forecast the day before.

Over Poland the eclipse will be deep and partial, and what makes it unusual is its timing close to sunset. That means a low solar disc, and a view in which the eclipsed sun sits against the horizon line.

Northern Poland holds an advantage here over the rest of the country, because it has something available nowhere else: an open, unobstructed western horizon over water. The best conditions will fall on the western stretches of coast, from Świnoujście to Kołobrzeg, and aboard vessels afloat. In Masuria the larger lakes aligned east to west produce a comparable effect.

Observation demands discipline. Looking at the sun, even eclipsed and low, requires purpose-made solar filters, not sunglasses, survival blankets or smoked glass. Aboard a vessel a second rule applies: whoever is not helming does the watching. A brief flash-blinding on watch ends worse than a missed phenomenon.

The month in balance

- August should generally favour time outdoors and on the water, and the weather has a chance of being less capricious than July, Damian Zbieg concludes. - That does not mean it will be calm all month. Violent storms in this kind of pattern appear locally and fast, which is why it is worth following warnings for thunderstorms, heat and fire risk.

The last of these tends to be dismissed in the north, though it should not be. Coastal pine forest, dune scrub and the woodlands of Warmia and Masuria dry out rapidly after a run of hot days, and in such a period every barbecue, cigarette end or campfire carries real risk.

Region by region

• West Pomerania

The stretch from Świnoujście to Kołobrzeg is the most exposed to flows from the western and north-western sector, so it will feel the weekend change earliest. It is also the best place in the country to watch the eclipse on 12 August, because here the western horizon lies entirely over water.

• Central Pomerania

Ustka, Rowy, Łeba and Słupsk. The stretch most exposed to the thermal contrast between land and water, and therefore to fast-developing storms coming ashore. It is also the area where upwelling occurs most often, on which more below.

• East Pomerania and the Gulf of Gdańsk

The Gulf of Gdańsk follows its own rules. Partly sheltered by the Hel Peninsula, it carries a lower sea than the open Baltic, but the sea breeze develops very regularly here and can surprise with its strength in the afternoon. During a hot week it is worth remembering that with winds from the eastern sector, water temperature in the gulf can drop sharply.

• Warmia and Masuria

The country's largest inland waters behave differently from the sea. There is no classic sea breeze here, but the risk during storms is considerably greater: the lakes are ringed by forest, so a squall emerges from behind the treeline without warning, and the distance to a safe shore is often greater than it looks from the deck. When storms are forecast on the Masurian lakes the same rule applies as at sea, only the margin of time is shorter still.

• Kuyavia and Pomerania

The region furthest from the sea in this survey, and therefore closest to the figures recorded in central Poland. Here the heatwave will register more distinctly than on the coast, and neither the Vistula nor the Koronowo Reservoir provides a cooling effect comparable to the Baltic.

What it means for sailors? A high does not mean no wind

Under high pressure and a weak gradient, the Polish coast is governed by the sea breeze. Land heats faster than water, the air above it rises, and cooler air from the sea moves in to replace it. The result is an onshore wind building through the late morning, peaking in the early afternoon and dying away before evening.

- The sea breeze is the only wind on this coast you can plan by the clock. It starts before noon, peaks in the early afternoon and fades before evening. Under a high it is the breeze, not the general forecast, that decides what we find on the water, says Damian Zbieg.

In practice mornings and late evenings are the calmest, with the most predictable sailing window running from roughly midday into the early afternoon. Sea breezes on this coast can reach several Beaufort and shift through the day, typically veering clockwise.

Heat and storms are one hazard, not two

With violent storms forecast to return, what matters is not the storm itself but what precedes it. Over water the first signal is often a darkening wall on the horizon and a characteristic shelf cloud, ahead of which a gust front can arrive a good fifteen minutes before any rain.

The rule for small craft does not change: when storms are forecast, do not go beyond the range of a fast return to harbour or moorings. "Fast" is measured in minutes, not hours, because that is how much time there is between the first sign on the horizon and the arrival of the gust. On the Masurian lakes, where forest hides the storm line, there is less time still.

The water can drop away beneath you

Water temperature deserves separate attention. Under high pressure with winds from the eastern and north-eastern sector, upwelling sets in along the Polish coast: cold water is drawn up from deeper layers to replace surface water pushed offshore. Sea temperature can then fall by several to more than ten degrees within a single day, under entirely summer conditions on the beach.

- Upwelling on the Polish coast catches people out more than anything else, because it happens in beautiful, sunny weather and gives no warning sign on the beach, Damian Zbieg notes. - The wind blows off the land, people see a calm sea and walk into water that has become more than ten degrees colder overnight.

For sailors and swimmers this is not a curiosity but a safety factor. Immersion in water below fifteen degrees triggers an involuntary gasp reflex and loss of manual dexterity within minutes, regardless of what the thermometer on deck reads.

Three things before casting off

In weather like this, three checks are worth making before every departure: current meteorological warnings, a forecast covering the next few hours rather than the whole day, and the actual water temperature where you intend to sail. A lifejacket worn before departure, rather than stowed under a thwart, completes the list. August weather favours sailing, which is good news, but it also favours overestimating one's own capacity.

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