No heat records in sight (yet) despite the ‘dog days’

The term "dog days" derives from the constellation Canis Major, specifically its main star, Sirius. The dog days begin with the first rising of this star, visible from Earth. The ancient Greeks and Romans believed that the heat during this period was due to the combined influence of Sirius and the sun. Keystone / Anthony Anex

The dog days—traditionally the hottest days of the year—began on Tuesday. However, the weather service Meteonews predicts that Switzerland is unlikely to see new temperature records in the near future.

According to meteorologist Roger Perret in the Meteoblog, temperatures in northern Switzerland are expected to rise in the coming days. On Saturday, temperatures could reach 30 degrees Celsius or higher, similar to current conditions in southern Switzerland. However, the annual records of 33.5 degrees Celsius on July 15 in Chur and 34.3 degrees Celsius on Monday in Biasca, Ticino, are likely to stand for now. By Sunday, temperatures in the north are expected to fall well below 30 degrees again.

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Potential for heat records remains

The dog days will last until August 23. According to Perret, it is “quite possible, almost to be expected” that the heat records for 2024 could still be broken. The hottest days of the year typically fall between July 23 and August 23. The Earth’s surface warms up slowly over the course of the year due to its inertia, and a stable high-pressure system often occurs in the region during this time.

“Dog days”: an astronomical origin

Perret explains that the term “dog days” derives from the constellation Canis Major, specifically its main star, Sirius. The dog days begin with the first rising of this star, visible from Earth. The ancient Greeks and Romans believed that the heat during this period was due to the combined influence of Sirius and the sun.

However, the precession of the Earth’s axis has shifted the timing of the dog days by about four weeks. Now, the rising of Sirius can only be observed at the end of August. Despite this, the hottest weeks of the year are still traditionally referred to as the dog days. Precession is defined as the gradual backward movement of the point of intersection (vernal equinox) between the celestial equator and the ecliptic, caused by the gyroscopic movement of the Earth’s axis over approximately 26,000 years.

Adapted from German by DeepL/amva

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