An exceptionally long heatwave

Yesterday, 12th August, was still officially a hot day, but it's unlikely we'll experience the same degree of heat today, says the on duty weather forecaster at the Finnish Meteorological Institute. Should the magic number of 25.1°C not be reached today, then the duration of the heatwave will come to a total of 38 days. Finland has only once before experienced a similar heatwave since records began in 1961. The heatwave in the summer of 1973 also lasted for 38 days. This year, the ground temperature reached at least 30°C on a total of 22 days. This is the most frequent since 1961. With regard to individual weather stations, the longest periods of continuous hot weather this summer were recorded at both Utti in the Kuovola region and Lepaa in the Hattula region, where 26 consecutive days of hot temperatures were recorded between 17th July and 11th August.

Similar heatwaves in 2003 and 2010

Owing to the persistent and long-lasting periods of high pressure often encountered during the Finnish summer, local temperatures can repeatedly hit 25°C. Week-long periods of hot weather are relatively common in certain regions, but are not usually repeated every summer. Periods of hot weather lasting a fortnight or more are especially rare and occur on average no more than once every ten years. We can begin to talk about an exceptional heatwave when hot temperatures are reached for three weeks in succession. Prior to this summer, this has only occurred in 1973, 2003, and 2010 since records began in 1961.

The heatwave experienced this summer is most similar to those in 2003 and 2010.  As was the case in 2003, this year's June heatwave was felt across the entire country. In contrast, the 2010 heatwave was mostly observed in the country's south and central regions. In Lapland, the average temperature in summer 2010 was close to the level normally expected for that time of year. However, hotter temperatures were recorded in 2010 than either this year or 2003, with records being broken in many parts of the country.  Finland's all-time record high temperature of 37.2°C was observed on 29th July 2010 at Joensuu Airport in Liperi. A new record for the month of August was also set in Puumala, Heinola, and Lahti, where a temperature of 33.8°C was recorded. So far, the hottest temperature recorded this summer was 32.8°C at Pori train station on 4th August.

Hot days are becoming more common

There have so far been 50 hot days this year, whereas the annual average is 36 days.  The record for the number of hot days was set in 2002, when a total of 65 days were observed.Finnish summers are already hotter than before and, should the rise in greenhouse gas emissions continue, this trend is not likely to change Hot summer days are increasingly common and periods of hot weather are getting longer. It is estimated that the number of hot days will triple or quadruple over the course of this century. "Very hot" days, when the average temperature is more than 24°C, were a rare occurrence between the years 1971 and 2000. By the end of this century, it is estimated that very hot days will be experienced more often than every other year. "It is predicted that owing to the change in climate, by 2010 temperatures similar to those seen in July 2010, or even hotter, will be encountered up to once every 10-15 years. Indeed, there is an 80% chance that at least one July will be as hot as this summer's between now and 2050", remarks researcher at the Finnish Meteorological Institute Kimmo Ruosteenoja.

Hot temperatures can lead to serious health problems

Hot temperatures pose a health risk to vulnerable groups such as the elderly and people suffering from chronic illnesses. At most risk are those suffering from heart, vascular, and respiratory diseases, diabetes, kidney diseases, Parkinson's disease, memory problems, mental health difficulties, and substance abuse issues.We do not yet know the full effects of this year's heatwave on people's health. "It's extremely unlikely that we'll see similar effects to those encountered in the summers of 2003 and 2010", comments Virpi Kollanus, researcher at the Finnish National Institute for Health and Welfare (THL). Research has shown that the heatwaves in those years lead to the premature deaths of several hundred people. In particular, there was an increase in the mortality rate of people over 75 years of age and those suffering from a range of chronic illnesses.

Elderly people living in some form of care home were at more risk of dying than those living elsewhere. This can be explained by the fact that elderly care homes look after the frailest individuals, and those who would otherwise be more prone to being negatively affected by hot weather. There is, then, cause for care homes and similar institutes to be better prepared to deal with the effects of hot weather.

Finns do not usually view hot weather as a risk factor

In Finland, hot weather is not normally viewed as a matter for concern in regard to the health of the nation. In addition to the need for health and welfare institutions to take proactive and carefully planned actions in order to be prepared for such conditions, there also needs to be a more general increase in our understanding of the dangers associated with hot weather. For its part, the Finnish Meteorological Institute issues hot weather warnings in an attempt to increase awareness and prepare the general public and those in decision-making positions in order to help prevent heat-related health problems.

"We must improve our readiness to deal with hot weather. Alongside an increasingly elderly population, we are going to see longer and more frequent spells of hot weather, and the impact on our nation's health will be significant", the researcher at the Finnish National Institute for Health and Welfare points out.

Further information:

Finnish Meteorological InstituteFor the latest weather forecasts, call the 24 hour meteorology service on: +358 (0)600 1 0600 (€ 4.01/min + local call charge)For climate statistics, call: +358 (0)600 1 0601 (€4.01/min + local call charge)

National Institute for Health and WelfareResearcher Virpi Kollanus, tel. +358 (0)29 524 6392, virpi.kollanus@thl.fi

Hot summer weather: http://ilmatieteenlaitos.fi/kesa-2014Health risks associated with extreme temperatures: http://ilmatieteenlaitos.fi/aarilampotilojen-terveysvaikutuksia

The adverse effects of hot weather and being prepared: http://www.thl.fi/fi/web/ymparistoterveys/helle

*All data collected since 1961 has been made digitally available.