Beat the Chill: Escape Boredom in the Bitter Cold!

While the nearby landscape is blanketed in snow and temperatures fall well below freezing, the hills here appear to challenge natural laws. How can it be that even during the coldest winter nights, the ground remains unfrozen, and green grass can still be found growing?

Smoking Boreč in the Bohemian Central Highlands

One of the most famous ventarols is Boreč hill (449 m), located around 4 kilometers west of Lovosice. The hill’s surface is adorned with shrubs and trees surrounding rocky crevices, where clay and icicles can be found. From some rock openings, white steam rises visibly, especially noticeable during colder weather. The hill retains heat during summer, acting like a large heat accumulator.

In winter, the cold air enters the cracks of the hill. This air heats up and rises, creating a stable temperature at the openings at the top of Boreč, ensuring it never drops below 9°C. If you want to visit Boreč, start from the village of Režný Újezd, located at the northeastern foot of the hill. It’s here that you can find the circular nature trail leading to your destination.

Silver Hill in the Lusatian Mountains

The air movement through rocky fragments is technically known as microexhale. This natural occurrence can also be seen in winter on Silver Hill (600 m) near Česká Kamenice. Unlike Boreč, Stříbrný vrch has been impacted by human activity due to basalt stone mining that ceased in 1973. Similarly, in the nearby Zlaté vrch quarry (657 m), basalt columns were found. Harsh weather conditions have led to erosion and water pouring into crevices, creating a maze of vents and cavities. You can reach Zlatý vrch by following a red trail from the car park located in the village of Líska. The Silver Hill can be accessed via an unmarked trail that circles around Zlatý vrch.

Homole Hill in Broumov Region

Rising slowly from the Šonovský brook valley near the village of Shawn is the somewhat unnoticed but still significant hill known as Homole, also referred to as Shonov Volcano. However, as we already learned, it is not a volcano. The ventarole phenomenon plays a role here too. At the hill’s summit, there is a relatively shallow pit where, on cold days, warm air vapors escape. A blue trail from Šonov will guide you to this so-called Šonov volcano, starting at the bus stop “Šonov, ZD”. It’s around 2 km from this point.

The Robber Cave in Olešnice near Ústí nad Labem

The Robber Cave is situated near Velký Březno, close to Ústí nad Labem. It’s an expansive fissure cave formed through the shifting of broken rock blocks (phonolite) on the steep slope of Zámecký vrch. In winter, the cave remains warm and the surroundings experience no freezing.

The Robber’s Cave is recognized as the largest cave in the Neovolcanoes region of the Czech Republic. It is also one of the largest fissure caves in the country, spanning a total of 130 meters in length. It descends 36 meters from its entrance, with passage widths ranging from 20 centimeters to 2.5 meters. The cave reaches a maximum height of about 8 meters. During war times, local residents would hide their valuables here, and today, bats and wrens seek refuge and hibernate in this warm cave. It is often accessed by animal trails, as animals seek it out in freezing temperatures to warm up.

Halda Ema in Ostrava

Our final suggestion is Halda Ema located in Ostrava—this isn’t a ventarol, but rather a burning heap of tailings. The burning occurs naturally as a result of spontaneous combustion, which happens as large amounts of material were deposited over time in the landfill. The internal temperature within the heap can rise remarkably high, reaching up to 1,500 degrees Celsius. This temperature is comparable to what is found in glass furnaces when melting silica sand. Despite the ongoing fire within the tailings, Halda Ema is accessible to the public. Visitors seeking amazing views can climb this artificial hill and appreciate stunning panoramas of the city from a height of 315 meters.

Warm Hole near Sternberk

An intriguing natural phenomenon can be discovered in the forest between Bělkovice-Lašt’any and Jívová. Here, warmed air escapes to the surface through a warm hole. This location is especially remarkable in winter when snow won’t remain on the hole, and you can see steam rising from it. Experts believe that a network of fissures exists inside the hill, connecting with the holes in the valley below. In winter, air heated by the Earth’s internal warmth to around 7 °C rises up, while in summer, cooler air flows down from the fissure into the valley. The warm hole is tucked away in a secluded spot, in the middle of the forest above the Belkovice valley. You can reach it via a steep climb from the Truskovice stream or from the Jaroslav springs situated between Horní Boudou and the village of Jívová.

Unfrozen hills are frequently tied to various legends. Historically, people thought supernatural entities inhabited these spots, or that they were either cursed or blessed. Certain hills were considered places of healing, where individuals visited to gain energy or recover from ailments.