Autumn 2021 - General Discussion

Brilliant news, thank you so so much. Best post from you in a long time.

Not rain and gales anyway, no thank you

Unusual to see burnt grass in late September. Today Could be like a July day during a drought.

Meanwhile despite being an anomalously dry and warm month to average, it has also been an often cloudy month (which is part of, not the only reason, why I express hatred for it). The limited stations' sun data I have are only around 40-60% of their average September sunshine with Cork Airport at only 58.7 hrs which is currently below its cloudiest Sep on record (2016, 68.4 hrs) but I expect it to go above that. Dublin was less than 50 hours before last Sunday, fortunately this past week has had some reasonable days with sunny spells and now almost 80 hrs which is still some way below average but an improvement at least.

Well we won't have much of a winter this year. This very warm September has effectively aborted it while its still in the womb imo. Autumn this year oct 2021- March/April 2022.

I'm not ignoring those signals. They are good signals for a cold winter. But the warmth now could be setting the tone for the coming months. That overall tone will imo override any cold winter signal.

We've been here many times before regarding warm Septembers in recent times and in each of those I thought we would have a mild winter. I see no reason why this year will be different.

If we are to get anything in the way of cold this winter, December imo is our best hope. But overall a mild one.

From September 10th. Last paragraph, the tone,its about the tone.

I thought back in September 2006 that we were being set up for a mild winter. Lo and behold thats what happened.

I barely remember the winter's of the mid 'noughties' tbh because they were, by and large, largely forgettable.

You like wet stormy winters. I'm surprised you don't remember winter 06/07.

Yep looks like we are on the brink of kissing summers last vestiges goodbye for another year. Another lovely day today though clouded over a bit for now here, still warm for the time of year @ 19.2C

Please jebus hold off the rain at least next Sunday week morning (marathon in Belfast).

I looked through the Phoenix Park data since 1855-56 and analysed Winter mean temperatures along with the Septembers that preceded those and this is what I found. Firstly, here's the graph of all the data although admittedly it is a bit messy and all over the place so hardly that helpful! Apologies again if quality is poor too, not sure what is with new Boards and posting graphs for me! The years 1959-60 and 1960-61 are not available.

Secondly, the average temperatures to keep in mind for September and Winter (DJF) are 13.4C and 5.1C respectively - these are 1981-2010 averages. When I combine the top 25 warmest Septembers at Phoenix Park, I get a following winter mean temperature of 5.4C which is slightly above the modern average. Out of those, there were 5 winters that had 4.1C or lower (at least -1C below 81-10 average). Another 2 contained at least one notable colder than average month but the winter as a whole was masked by the other month(s) being greatly milder.

Conversely, if I combine the top 25 coolest Septembers at Phoenix Park, I get a following winter mean temperature of 4.8C which is slightly below the modern average to the same extent as winters following the warmest Septembers are slightly above the modern average. Using older averages, this 4.8C mean temperature would be around average whilst the 5.4C would be even more greatly above average. Out of the winters following the coolest Septembers, there were 5 winters that had 4.1C or lower just like those following the warmest Septembers. However, there were no additional winters that contained at least one notable colder than average month whilst the winter as a whole was masked by other periods being greatly milder.

One last thing I tried was all the 'close to average Septembers' where the mean temperature is within half a degree (-0.5/0.5) of average whether below or above. The mean temperature for the winters following these Septembers I get is 5.0C which is basically average for a modern winter, slightly above for older averages. So 'close to average Septembers' are not biased to mild or cold winters following them. There are some notably very cold winters in this sample space such as 2009-10 and 1946-47 but equally there are some exceptional mild ones too such as 1997-98 and 1989-90.

I had decided on Phoenix Park for this analysis as whilst it does have UHI, its long-term record cannot be understated and can be useful for analysis such as this.

Apologies, had a feeling you were referring to that but wasn't sure. Out of the years named with September being warmer than the preceding August, no it has not happened before combined with April being colder than the preceding March. 2021 is pretty unique in that regard.

EDIT: However, for the Central England region, if that were to happen, it would join 1750 which also had this unusual occurrence of events but March 1750 was exceptionally mild rather than April being particularly cold.

Good work sryan. Perhaps there is some correlation regarding warm Septembers taking the years altogether not much but some. My main thinking on it is more along the lines of Septembers in the last 25 yrs or so.