Weather conditions in the first quarter of 2020 (January, February, March), heating degree days from April 2019 to March 2020.
Locally, the very warm January was already near record levels. Nationwide, it was the second warmest February since records began in 1864. The entire quarter was rather dry.
A very warm and dry January:
Switzerland recorded its third warmest January since records began in 1864 at altitudes above 1000 meters. On the northern side of the Alps, it was regionally the sunniest January on record. Across Switzerland, January was extremely dry. From January 1st to 25th, several high-pressure systems moved across Switzerland from the west and southwest, bringing plenty of sunshine to the Alps and the southern side of the Alps. Very mild conditions prevailed almost throughout the day in mountainous regions and on the Jura heights, while fog or high fog often lingered over the central and eastern Swiss Plateau. The persistent high-pressure weather was interrupted only on a few days by passing weak disturbances.
Stormy westerly winds: From January 26th, low-pressure systems dominated the weather in Switzerland. A stormy westerly flow developed during the night of January 27th to 28th. On the morning and evening of January 28th, widespread heavy showers fell, sometimes as graupel and snow, accompanied by lightning and thunder and stormy winds, with the snow line dropping to 400 meters in some areas. Wind gusts reached 55 to 90 km/h in the lowlands on the northern side of the Alps, up to 120 km/h in some regions, and 110 to 150 km/h at higher elevations. On January 29th, the stormy conditions continued with slightly lower gusts. The southern edge of the Alps was quite sunny with highs around 14 degrees Celsius. The last nighttime disturbance occurred from January 30th to 31st, while the entire country enjoyed several hours of sunshine during the day.
Monthly summary for January 2020: According to MeteoSwiss, the average January temperature across Switzerland was 2.4 degrees Celsius above the 1981–2010 average. In mountainous regions, January temperatures were 3 to 3.6 degrees Celsius above average. On the southern side of the Alps, January temperatures were widely recorded as being 1 to 2 degrees Celsius above the long-term average.
Precipitation in January on the southern side of the Alps and in the Engadine Valley was generally only 10 to 30% of the average, and in some areas even only 5 to 10%. In the rest of Switzerland, precipitation was generally only 30 to 60%, and locally around 70% of the long-term average.
Sunshine duration in January was 150 to 220% of the average north of the Alps and on the northern slopes of the Alps. In the rest of Switzerland, it generally ranged between 120 and 150% of the average. At the measuring stations in Bern, Geneva, Zurich and Basel, which have over 100 years of records, January delivered new sunshine records.
Second warmest February since records began:
February was very warm and stormy, ranking among the second warmest Februarys nationwide since records began in 1864. In addition to the monthly record, numerous daily high temperatures were broken, reaching 18 to over 20 degrees Celsius in some areas. February was frequently dominated by southwesterly winds, which brought mild or subtropical and humid Atlantic air masses to Central Europe.
With this imported heat, the average daily temperature in Switzerland remained well above normal from February 1st to 24th. At nearly 40 weather stations, the average daily temperature reached new February records. These were mostly recorded on February 3rd, 23rd, and 24th.
Stormy February: February 2020 was unusually stormy. On the Säntis and Chasseral mountains, 25 storm days were recorded. At both measuring stations, it was the stormiest February since records began in 1981. In the lowlands on the northern side of the Alps, the stormiest February since records began in 1981 was recorded in some areas.
Three winter storms swept across Switzerland in the first half of February: Petra on the 4th, Sabine on the 10th, and Tomris from the 13th to the 14th. Storm Sabine, on February 10th, was the strongest. In the Swiss Plateau, wind gusts widely reached 90 to 120 km/h. On the Jura Mountains, maximum gusts climbed to 140 to 160 km/h, and on the summits, to 160 to 200 km/h.
Forest fire danger in the south: Following a very dry January, the southern side of the Alps also received extremely below-average rainfall in February. Widespread precipitation fell below 10%, and in some areas even below 5% of the normal amount. This persistent lack of precipitation led to a high risk of forest fires on the southern side of the Alps. A similar period of low rainfall during January and February is expected in southern Ticino approximately every 15 to 20 years.
Monthly summary for February 2020: According to MeteoSwiss, February's average temperature was 1.6 degrees Celsius above the national average, which is 3.9 degrees above normal. This makes it the second warmest February in Switzerland since records began in 1864. The southern side of the Alps experienced a record-breaking February. In the lowlands of Ticino, the average February temperature reached 8.1 degrees Celsius, almost 4 degrees above the 1981–2010 average.
Precipitation amounts on the southern side of the Alps remained mostly below 10%, and locally even below 5% of the average. In the Engadine, amounts ranged between 60% and 100%. In the rest of Switzerland, the regular southwesterly winds with their moist, mild Atlantic air masses brought abundant precipitation. Total rainfall reached 150% to 200% of the average in many areas, and regionally even 200% to 250%. Sunshine duration in February rose widely north and south of the Alps to 120 to 140% of the norm. Western Switzerland recorded up to 150% regionally, and central Switzerland locally up to 160% of the long-term average. In the Alps, sunshine duration generally ranged between 80 and 100% of the norm.
A Changeable March:
March was predominantly dominated by high pressure. The average temperature across Switzerland was 0.8 degrees Celsius above the 1981–2010 average. Precipitation remained below average in many areas. During the first ten days of March, low-pressure and high-pressure systems alternated every two days. Rain fell almost daily in many parts of Switzerland.
From March 11th to 20th, high-pressure systems extending from the Atlantic to Europe dominated the weather, bringing mild air masses to Switzerland with westerly and southwesterly winds.
During the first significant heat wave on March 11th and 12th, the average daily temperature rose 5 to 7 degrees Celsius, and locally 8 to 10 degrees Celsius, above the average. During the second heat wave from March 16th to 20th, accompanied by plenty of sunshine, the average daily temperature rose 4 to 8 degrees Celsius above the average in many places.
The most significant drop in temperature of the winter season: On March 21, a strong high-pressure system built up over Scandinavia, which then moved slowly southeastward in the following days. Cold continental air flowed along its southern flank toward Switzerland. The average daily temperature fell 3 to 5 degrees below normal on both sides of the Alps, and locally by 5 to 7 degrees.
In Switzerland, the average daily temperature never fell so far below normal during the entire winter of 2019/2020. The cooling was particularly pronounced on the southern side of the Alps. In the low-lying areas on both sides of the Alps, there were several nights with frost. Minimum temperatures at a height of 2 meters reached 3 to 6 degrees below freezing in some areas. Directly above the ground, temperatures dropped to 7 to 10 degrees below zero in many places.
Monthly summary for March 2020: According to MeteoSwiss, the average temperature in March across Switzerland was 0.8 degrees Celsius above the 1981–2010 average. North of the Alps, it was generally 0.5 to 0.9 degrees Celsius above average, and locally 1.0 to 1.2 degrees Celsius above average in western Switzerland. In the Alps, temperatures ranged from 0.8 to 1.3 degrees Celsius above average, while on the southern side of the Alps they were only 0.1 to 0.6 degrees Celsius above the long-term average. Precipitation amounts in March generally reached 60 to 90% of the average. In the Engadine and the Davos region, amounts were around 100%. In the lower Valais and the Lake Geneva region, values rose to 100 to 120% of the long-term average. Sunshine duration in March generally increased to 130 to 150% of the average north of the Alps. In the Alps, sunshine duration generally ranged between 100 and 130% of the average. The southern side of the Alps mostly recorded 90 to 100% of the long-term average.
