Hints of coming seasons for both cities as September ends

Over the past few days both Sydney and Jyväskylä have had a taste of what's to come in the next few months. While temperatures soared to 30C and above in Sydney, Jyväskylä struggled to get above 5C.

Strong northwesterly winds again helped temperatures climb in Sydney. Saturday September 28 saw 30.4C measured at the airport. Sunday returned to cooler temperatures with a maximum of 22.3C after a southerly change, but September was rounded out on Monday with the return of northwesterly winds. The 30C mark was almost reached again, falling just short at 29.2C.

Hitting 30C on Saturday made it the 6th day of September above that point. The graph below shows the number of September days where the maximum temperature was below 20C (in blue) and above 30C (in red) in the period 2009-2013.

Number of September days at Sydney Airport where the maximum temperature was below 20C and above 30C for the period 2009-2013

It's easy to see this was the only year of the past 5 years where there were more days above 30C than below 20C. There were also an additional two days above 29C, including September 5 when 29.9C was recorded, that are not included in this graph.

Overall the minimum and maximum averages for September at Sydney Airport were easily the highest since 2009. The average minimum was 13.7C, compared to an average of 12.0C for 2009-2012. The average maximum was 25.1C, compared to an average of 22.1C for 2009-2012.

After that warm start to September for Jyväskylä, it certainly cooled down towards the end of the month. It didn't go above 10C for the last 8 days of the month. The first sub-zero recording occured late in the evening on September 29 when the temperature dropped to -1.2C. This was the latest date for that to happen in the last 5 years, as highlighted in a previous post I made.

Of the past 5 years, this year had both the highest number of days above 20C (3) and the highest number of days below 10C (8). The lowest daily maximum for a September day in the last 5 years was also recorded, 5.3C on September 25.

Overall the minimum and maximum averages for September in Jyväskylä were, well, average for the last 5 years. The average maximum of 14.5C slotted right in the middle for 2009-2013. The average minimum of 5.3C was the second lowest for the 5 year period.

Because I like to pick out unusual observations, let's look at September in two 15 day blocks. The graph below shows the average minimums and maximums for a September 1-15 block and for a September 16-30 block.

Average minimums and maximums for two 15 day blocks in September for Jyväskylä for the period 2009-2013

Even though the overall average for September was fairly normal, it's actually quite odd if we look at it this way. Firstly, the first 15 day period for 2013 easily had the highest average maximum and the lowest average minimum, as I pointed out in a post a couple of weeks ago. But look at the second 15 day block. Not only is the average maximum the lowest of the 5 years, the average minimum is also the highest.