Temperature records

Records attract attention, and they are easy to get wrong. This guide explains Sweden's national temperature records, why SMHI is careful about approving them, and how Temperaturkollen uses words such as "warmest", "coldest" and "record".

Sweden's national records

According to SMHI, the highest temperature measured in Sweden is 38.0 °C. It has been reached twice: at Ultuna on 9 July 1933 and at Målilla on 29 June 1947. The lowest temperature measured at an official Swedish weather station is −52.6 °C, at Vuoggatjålme on 2 February 1966.

Why records need care

A record is only as good as the measurement behind it. A thermometer that gets direct or reflected sunlight shows too high a value, and SMHI notes that some old types of shelter could read up to about five degrees too high. For the months February to October, SMHI has not approved records from stations judged to have had inadequate radiation shielding. Good ventilation around the thermometer is also required.

From 1927, minimum thermometers were compared with a reference thermometer and their readings corrected, but the corrections were not always applied in the same way, and routine corrections stopped around the mid-1980s. Some values have been corrected later in SMHI's database and can therefore differ from figures that were published at the time.

Location matters too. SMHI explains that stations in valleys can be very warm on summer days and very cold on calm, clear nights, so where a station stands affects which records it can set.

Records on Temperaturkollen

Our records are station records: the highest or lowest value in one station's series in SMHI's open data. They are not necessarily the most extreme temperature ever measured in a town, because older measurements may come from another station or may not be in the open data at all. The rules:

• Warmest and coldest day of a year are the highest daily maximum and the lowest daily minimum, shown separately and labelled. Their measurement window is 18–18 UTC.
• "Warmest year" and "coldest year" need at least 10 complete years at the station.
• The word "record" is used only when the station has at least 20 complete years.
• An annual mean only counts when all 12 months are complete.
• If a station has moved 2 times or more, a warning says that the series may contain level shifts caused by the moves.

We do not draw trend lines or make claims about trends from a single station. A warm year at one station is a fact about that year, not a forecast.

SMHI's lists of national records by month are on its records page, linked below. Temperaturkollen never presents a station record as a national record.