May 2014 Review - Jyväskylä

May 2014 was a weird month for Jyväskylä. The warmth of spring in April disappeared at the start of the month and it seemed like summer was just a distant dream. Then suddenly, the weather changed. Temperatures climbed to near record highs and it felt like summer had finally arrived. However, after a bit more than a week, the heat disappeared again.

In the end, May turned out to just above average in terms of temperature. It was also quite wet. The monthly total was more than double the average.

May averages at Jyväskylä Airport for the period 2009-2014

As shown in the graph above, this year had the lowest average maximum of the past 6 years. According to FMI, the average temperature for the month was 9.5C, down 3C on the record of 12.5C from 2013. This is compared to my recordings of 8.9C and 11.6C respectively. FMI's 1981-2010 average for Jyväskylä stands at 8.9C. Only 2 of the past 10 Mays have been below that average.

This year saw two of the hottest May temperatures in at least the last 6 years. Both May 19 and 24 got to 29.3C. The warm period also brought the highest minimum of 14.1C, recorded on the 20th. The cold start to the month saw the lowest overall temperature and the lowest maximum. It only climbed as high as 5.2C on the May 4, and it dropped to -6.4C on the 7th. These were the lowest respective figures in the past 6 years.

Nationally, Heinola saw the highest temperature of the month. As mentioned in a previous post, the 30.8C recording there on May 19 was only 0.2C off the all time May record. May 5 was responsible for the coldest temperature when it dropped to -16.3C at Kittilä.

May this year had 3 distinct periods. The first 16 days were unusually cold. The next 9 were unusually warm and the remaining 6 were just below average. FMI reported that the cold seen during the first couple of weeks is only seen in May once in a decade on average. The graph below shows the average daily temperature throughout each May in Jyväskylä from 2009 to 2014.

Average daily temperatures for May at Jyväskylä Airport in years 2009-2014

It's clear to see from the graph that 2014 really stands out. Not only did it have many of the lowest daily averages, but also many of the highest daily averages.

Some other interesting, and somewhat contrasting, observations from May 2014 include:

• There were 4 days with a minimum below -5C. There were no May days below -5C between 2009 and 2013.
• There were 10 days with a minimum below 0C. This was the highest number in the past 6 years.
• There were 13 days with a maximum below 10C. This was easily the highest in the past 6 years (next highest was 5 in both 2010 and 2012).

On the other hand...

• There were 6 days with a minimum above 10C. This was also the highest number in the past 6 years.
• There were 5 days with a maximum above 25C. This was the equal highest (with 2010) number in the past 6 years.
• There were 7 days warmer than the warmest day in both May 2011 and 2012.

Rainfall was well above average for the month. Most of the southern half of the country recorded more than the average. FMI recorded a total of 114mm at Jyväskylä Airport. This was almost 100mm more than the figure for last May and more than double the 1981-2010 average of 44mm. My own recordings, calculated using FMI pages on a daily basis, totalled 124.6mm.

There were a total of 18 days with rain recorded with totals ranging from 0.1mm to 28.1mm. A 7 day period between May 8 and 14 was the longest streak of rain days. May 21 to 24 was the longest dry streak. May 26 was responsible for the highest daily total while May 25 also saw 24.2mm.

Finland saw around 25,000 lightning strikes throughout the month. This was above the average of 8,500. May 19 and 25 accounted for around 13,000 and 9,000 strikes respectively.