Cool start to May makes way for warm weather

Summer weather has arrived at last in Finland. Yesterday was the first official 'hellepäivä' as temperatures climbed above 25C in locations in southern Finland for the first time this year. A high pressure system is sitting east of the Finnish-Russian border and is generating warm south easterly winds across most of the country.

The highest temperature yesterday was recorded in both Turku and Heinola. It reached 25.7C in each city. Other locations to reach 25C included Hämeenlinna, Kokemäki, Kouvola and Lahti.

In Jyväskylä it hovered around 23C for a few hours in the afternoon, peaking at 23.6C. It was the first day above 20C since September 14 last year, ending a run of 243 consecutive days below that mark. The table below shows that this is actually the lowest such figure of the past 5 winter periods.

Last and first days above 20C and the number of consecutive days below 20C for the past 5 winter periods

The warm weekend in Jyväskylä was quite a change from Friday when it only reached 9.1C. It was 10C warmer on Saturday getting to 19.1C.

Today has been even warmer than yesterday with temperatures climbing above 25C in locations from Helsinki all the way up north to Oulu. Jyväskylä has reached around 29C, the first 25C+ temperature since August 8 last year. The all time record for May in Finland was close to being broken in Heinola. It got to 30.4C there, just off the record of 31.0C.

On the grounds of the University of Jyväskylä on May 18

Small plane over Jyväskylä on May 18

Sydney has also been enjoying some warm weather. The temperature reached 26.2C at the Airport this afternoon, the warmest in almost 3 weeks. Friday to Sunday saw tops of 25.4C, 25.7C and 24.2C. This heat is rather unusual for this time of year and it looks like it will continue, possibly all the way into early next week.

Minimums have also been higher than normal, hovering between 11.7C and 13.4C for the past 6 days. One observation worth pointing out is that it still hasn't dropped below 10C at the Airport yet this year. The past 5 years had all seen at least one minimum below 10C by May 15 and looking at Bureau of Meteorology records, this is the latest date since 2007, when it first dropped below 10C on May 23.

In fact, since temperature records began at the Airport in 1939, there have only been 4 years in which it hadn't dropped below 10C by May 19. Other than 2007, 2003 first saw a temperature below 10C on May 29, it was May 23 for 1989 and May 21 for 1974. The current weekly forecast for Sydney doesn't show any minimums below 13C, so breaking the 2003 record is definitely possible.