May 2015 Review - Jyväskylä

Jyväskylä saw a cool May in 2015. The typical first burst of summer just never came. It was the coldest May, in fact, since 2008 at Jyväskylä Airport. The cooler temperatures weren't seen during the nights, but during the days, as maximums were well below figures from recent years.

Jyväskylä wasn't the only location in Finland to endure an extended spring. Almost all of the southern half of the country experienced below average temperatures. The southern coast and inland between Helsinki and Turku saw the biggest difference below average; up to 1.5C. Parts of Lapland, however, especially in the east, were slightly more than 1C above average.

Rainfall was above average at Tikkakoski, but there was very little storm activity throughout Finland during the month.

May figures from the previous seven years are shown below.

May averages at Jyväskylä Airport for the period 2009-2015

With an average maximum of 13.5C, May this year was 4.6C cooler than the May of 2013, and 1C cooler than the next coolest figure from last year. The Finnish Meteorological Institute recorded an overall average of 8.7C for the month, against 8.5C from my recordings. The 8.7C figure was the first below the 1981-2010 average of 8.9C since 2008.

The highest recording of the month at Tikkakoski came on May 25 when it reached 18.9C. This was well below figures from recent years. The next lowest respective figure since 2009 is 22.4C in 2011, while 2009, 2010, 2013 and 2014 all recorded days above 25C. The coldest maximum was also the lowest seen in May in the years since 2009. May 2 reached only 5.1C, just below 2014's 5.2C on May 4.

The highest minimum of 10.0C on May 27 was above the respective recordings from 2011 and 2012, but still quite far below last year's 14.1C and 2010's 15.2C. The coldest temperature overall was recorded on the 4th. The -3.0C recording then was one of only two minimums below zero during the month, and sits in the middle of the past seven years.

Extremes in Finland for the month ranged from -12.4C at Enontekiö's Näkkälä station on May 5 to Mikkeli's top of 21.7C on the 26th. The absence of any hellepäivät, or days above 25C, was the first instance for a May since 1998.

Daily minimums and maximums against rainfall for May at Jyväskylä Airport

Rain measured 53.6mm at Tikkakoski during the month. FMI recorded a total of 51mm. Both figures are above the 1981-2010 average of 44mm, but well below last year's 124.6mm, which was only just below the overall record.

May 13 was the wettest day when 22.7mm fell. It was also the wettest day of the year to date, and only the second day of the year with a total above 10mm. There were 20 days of precipitation, but the 14th of the month was the only other day to see more than 5mm. It was also part of a 10 day rain streak. Dry weather during the month was scarce. The longest dry streak was only two days, which occurred three times.

Despite the high number of rain days and the whole country recording above average rainfall totals, storm activity was rare. FMI reported only 331 groundstrikes. This is the third lowest figure for a May since 1960. In comparison, FMI reported over 25,000 lightning strikes for May in 2014.

May 2015 Review - Sydney

May in 2015 at Sydney Airport saw average temperatures a little closer to the long term figures when compared against the previous two years. They were still higher than average though. Rainfall was more than four times last year's figure, and the month was the wettest May of the past few years, but it still fell short of the average.

May averages since 2009 are shown below against the long term values.

May averages at Sydney Airport for the period 2009-2015 plus the long term average

Other than 2011, Sydney Airport hasn't seen an average minimum for May below the long term figure since 1984. 2006 was the prior year for an average maximum below the 20.0C average. The Bureau of Meteorology recorded average figures for May of 12.6C and 20.7C.

The highest temperature for May 2015 was 28.6C on the 5th. This was the hottest May day since 2007 and the seventh highest on record at the Airport. The warmest minimum was also unusually high. The May 3 recording of 19.0C, more typical of figures in March, was one of the highest on record as well. May 2 and 4, with minimums of 17.5C and 16.5C were also higher than the highest May minimum between 2009 and 2014 of 16.3C. 2012's figure was 14.3C, almost 5C less.

The lowest temperature of the month was 7.3C. That recording on May 14 was the coldest May temperature since 2011. Since 2009, only 2011 saw temperatures lower than that; there were four daily minimums below 7.3C then. The coldest day was the final day of the month. It only reached as high as 16.5C. This was, however, the second highest respective figure since 2009.

Daily minimums and maximums at Sydney Airport for May 2015

Rainfall totals for Sydney Airport were below average during the month. The calendar month saw 77.2mm while the Bureau recorded 85.8mm. The long term average is 98.6mm. 2014 saw far less with only 18.0mm. According to Bureau records, the 85.8mm total is the highest May total since 2011.

There were 13 days on which precipitation was recorded at the Airport. The wettest was May 2 when 27.2mm fell. The 1st and 22nd also recorded a daily figure above 15mm with respective totals of 17.2mm and 20.2mm. The longest dry streak was nine, from the 4th to the 12th, and is now the second longest dry streak of the year. May 19 to 23 all saw some precipitation, making it the longest run of rain days.

Wind gusts at the Airport were up during May this year comparing with 2013 and 2014. The strongest gust of the month came on the 22nd when a southerly at 87km/h was recorded. Earlier on May 13 there was a southwesterly at 69km/h recorded also. Both of these were higher figures than any gusts during the two previous Mays. May 18 was the calmest day when a strongest gust of only 22km/h was recorded. The south-southwesterly gust was the lowest strongest daily gust in exactly one year; May 18 in 2014 saw a strongest gust of 20km/h.

FMI changes forecast for Jyväskylä - summer on hold again

Where is summer in Finland? When will it arrive? Well, after predictions last Thursday and Friday by the Finnish Meteorological Institute it appeared that warmer temperatures above 20C would finally arrive in Central Finland tomorrow and Wednesday. On Saturday May 30, however, the slate was wiped clean and no longer was there the potential for the 25C barrier to be broken this week. Now the coming 10 days look more like what has been seen in Jyväskylä during the recent two weeks.

Such dramatic changes in forecasts are not that rare in the world of meteorology, especially for weather four or more days in advance, but this particular change is very disheartening. The potential for days above 25C in Jyväskylä ranges from mid-May until the very beginning of September, and for every day that we delve deeper into the summer without such weather, the less hopeful people are that it will come.

Despite the lack of 20C-plus days, Saturday May 30 was a beautiful day in Jyväskylä. It reached a top of 18.1C at Tikkakoski in the afternoon, making it the equal fourth highest maximum seen so far this year.

Another forecast error occurred on the last day of May. On the 30th there were predictions for rain during the morning and middle of the day for Sunday. These predictions on Saturday night had a confidence level of 90% and showed the potential for more than 5mm. A small band of rain did move north through Western Finland, but it was much less widespread than the predictive images shown through FMI's rain radar on Saturday night. In the end, nothing at all was recorded at Jyväskylä Airport.

The rest of Sunday also turned out quite nicely. The 16.7C maximum was more than 2C above Saturday's temperature prediction and pushed the run of consecutive days above 15C to seven.

Sunshine on dandelion flowers in Jyväskylä during the afternoon of May 31

According to forecasts now, tomorrow looks likely to be the warmest day of the next 10. Saturday June 6 could reach 17C, but all other days up until June 10 aren't predicted to go higher than 16C.

This kind of weather isn't really that unusual for Finland. Summers can be highly unpredictable and often have cool periods. Even the back half of June last year, for example, saw a 12 day run below 18C. At least in 2014's case, by June 12 Jyväskylä had already seen 15 days above 20C, seven of which also exceeded 25C. Let's hope warmer temperatures arrive in Jyväskylä soon...

Jyväskylä on the brink of summer, dry week in Sydney

The gradual arrival of summer in Jyväskylä this year has received a boost during this week. While that somewhat magical mark of 20C hasn't been surpassed yet, Monday through to Friday have seen maximums above 15C. This is the first string of five days above 15C since the middle of September last year.

The 20C barrier will surely be broken next week. Forecasts show Wednesday June 3 to be the first day. It has a current predicted maximum of 24C. The days following that are also predicted to be around 20C. With May ending on Sunday though, 2015 will be the only year since 2009 for Jyväskylä to not see a day in May above 20C.

One milestone for the year was surpassed on Wednesday May 27. The minimum at Tikkakoski held in double figures, right on 10.0C, for the first time since September 5. Compared to years since 2009, May 27 is the equal third latest. 2011 and 2012 didn't see a minimum at 10C or above until June 1 and 10, respectively. 2010, on the other hand saw the first occurrence on May 14.

Despite May 27's minimum at 10C, other minimums this week have been much lower at Jyväskylä Airport than predictions given by the Finnish Meteorological Institute last week. As a result, the overall average minimum for the month will be more than 1C lower than what had been predicted in my mid-month May progress post from May 19.

The sky over Jyväskylä on the morning of May 28

Another period of dry weather set in in Sydney this week. A run of five days of precipitation at Sydney Airport ended last Sunday and 0.2mm of rain this morning just before 8am is the only recording since then. Temperatures have also been fairly warm for this time of the year. Only Tuesday this week didn't exceed 20C. The long term average daily maximum for late May is around 19C.

The next few days will be more wintry though. May 31 through to June 5 currently don't have any predicted maximums higher than 18C and Tuesday June 2 could see morning temperatures dip to a chilly 6C. The minimum of 7.3C from May 14, one of only five minimums below 10C, remains the lowest so far this year.

Rain returns to Sydney, warmer in Jyväskylä

Rain returned to Sydney today. After a few weeks without a daily total greater than 2.2mm, the Airport picked up 19.2mm today, with most of it falling in the morning between 5am and 11am. It was the highest daily total since 27.2mm was recorded on May 2.

Very strong, gale force winds also struck the city. Southerly gusts over 70km/h were recorded from the mid morning up until the late afternoon. The strongest of 87km/h came at 12:26pm and was the strongest since the winds of the April 20-22 storm. It was also far stronger than any other gust seen in the Mays of 2013 and 2014. The previous strongest May gust since 2013 was 69km/h, recorded on the 13th of this month, only a week and a bit ago.

To round off a rather miserable day in the coastal city, temperatures were also down on previous days. It only reached 17.4C around 12:30pm at the Airport, putting it equal with May 13 as the coldest maximum of the month and the fourth lowest maximum for the year. May 20, however, saw only the second day of the month to break the 25C barrier.

The colour of green becoming more apparent at Jyväskylä's Rautpohja lake on May 21

In Jyväskylä, today has seen the third consecutive maximum above 15C for only the second time this year. After recordings of 15.7C and 15.5C on May 20 and 21, it came close to 18C today. May 6 is the only other day so far this year to go higher than 18C.

Showers drifted through Central Finland yesterday afternoon. Jyväskylä's city centre saw some rain fall around 6:30pm, but Tikkakoski didn't see any recordings. In the past month there have been only two blocks of two consecutive rain free days. May 20 and 21 was one of them along with the 4th and 5th of this month.

Temperatures will drop again tomorrow though. FMI forecasts a top of only 10C for Jyväskylä. The next 10 days still don't show any sign of breaking 20C either.

Contrasting averages for both cities so far this May

The first 19 days of May in 2015 have led to some contrasting averages for both Sydney and Jyväskylä compared to recent years. The two standout figures of the four are the average minimum at Sydney Airport, which has been well above figures since 2009, and the average maximum for Jyväskylä, which is on its way to the coolest recording of the past seven years.

Progressive average minimum for May at Sydney Airport for the period 2009-2015 plus the long term average

The progression of the average minimum has been unusual this year and, not surprisingly, it's above the long term average. May 2 and 3 saw the two highest minimums for May at the Airport since at least 2009. Even though May 14's 7.3C minimum was the lowest since 2011, the warm minimums have propped up the average. If those two recordings more normal, the average for 2015 would currently be sitting closer to that of 2013 and 2014. Forecasts show the average continuing to hover around 13C at least for the next week.

Progressive average maximum for May at Sydney Airport for the period 2009-2015 plus the long term average

The average maximum at Sydney Airport so far this month has been closer to normal. This is despite May 5 recording the seventh highest May temperature on record at the Airport. The 28.6C maximum was the highest May temperature since 2007. Other than 2007, only Mays in 1942, 1957 and 1994 recorded a higher maximum. It is actually the only maximum above 25C in the month so far though. The final average for the month will likely sit among the majority of recent years between 20C and 21C.

Progressive average maximum for May at Jyväskylä Airport for the period 2009-2015

Jyväskylä's relatively cool start to May has led to the average maximum dipping below all other years bar 2014 up until today. 2014's cold start made way for almost record highs on this exact day one year ago though and the dramatic increase in the average from the 16th is evident in the graph above. Unlike 2014, however, it doesn't look like Jyväskylä will be seeing any maximums at those levels. The forecast up until May 28 doesn't even show one day above 20C. If the predictions are correct, May 2015 will definitely have the lowest average since 2009.

Progressive average minimum for May at Jyväskylä Airport for the period 2009-2015

While the average maximum is on its way to the lowest of the past few years, the average minimum is looking likely to record the highest figure since 2009. Only two minimums have been below zero at this point of the month. This is lower than the whole of any May between 2009 and 2014. The 10 day forecast currently doesn't show any minimums below 5C either. Up until today, there have also been seven figures above 5C. 2010 had seen the same amount, but other years had a lower number of occurrences.

Summer still on hold in Jyväskylä, signs of winter in Sydney

Summer 2015 is taking its time to arrive in Finland. It was assured today that 2015 would record the latest date for the first temperature above 20C in Jyväskylä in the years since 2009. In the six years from 2009 to 2014, the earliest day of the year to record the first maximum above 20C has ranged from April 26 in 2011 to May 18 last year. The highest temperature so far in 2015 at Jyväskylä Airport is 18.1C, recorded on the 6th of this month.

The May 6 maximum is one of only three days above 15C so far at Tikkakoski this year. Going up to May 18, this is the lowest number of days for all years since 2009. 2009 and 2013 had seen 11 days by this point, while the average across the previous years is a bit over eight. May 16's maximum of 9.8C is a long way off the maximum of 28.3C on the same day in 2010 as well. 

The cooler temperatures are likely to continue too. The current 10 day forecast still doesn't show any days above 20C. Between 2009 and 2014, the highest respective May temperatures have ranged from 22.4C in 2011 to 29.3C last year.

In addition to the cooler weather, rain has also been around. Since May 6, only the 16th hasn't seen any precipitation recorded at Tikkakoski. The highest daily rainfall of the year was set anew on Wednesday May 13 when 22.7mm was recorded. This almost doubled the previous highest total of 11.6mm from the second day of the year. There were only four days in 2014 with a total over 22.7mm.

In Sydney, the past week has seen some early chills of winter. The past six days have failed to climb above 20C, equalling the longest run below the mark since a string of 13 days last August. The lower temperatures aren't really that unusual for this time of the year, but it's quite different from last May when some exceptionally warm weather arrived in Sydney.

Minimums for the past couple of days have also been fairly normal, in the low teens, but there was definitely a wintery feel about the afternoon of Wednesday May 13. Temperatures reached 17.4C at the Airport just after midday, but a southerly change dropped the mercury closer to 10C already before 4pm. A few showers made their way across the city as well, dropping 2.2mm at the Airport. Snow was even sighted near Goulburn, 170km southwest of Sydney. 

The late evening of the 13th saw temperatures drop below 10C for the first time this year and for the first time since mid-October last year. The following morning of May 14 recorded a minimum of 7.3C, the coldest May minimum at Sydney Airport since 2011.

After seeing 44.4mm fall on May 1 and 2, the following 16 days at the Airport have seen only 3.8mm more added to the monthly total. May 4 to 12 saw no rain and this is the second longest dry streak so far this year.