Should September be classed as a summer month?

[East Lancs Rain]

I personally think it’s time September was classed as a summer month now. It’s often warmer/sunnier than August and over the last two decades we’ve had a lot of warm/hot Septembers. In most places it’s only around a degree cooler than June on average. And in some coastal locations, September is actually a warmer month than June. For example, in Camborne in Cornwall,  June has an average high of only 16.9°C, while September has an average high of 17.4°C.

 

So often as soon as the schools go back the sun comes out. I was in the Cotswolds during the first week of September last year and it was absolutely scorching. 30°C and sunny on several days!

It always seems a bit early when as soon as 1st September hits the summer moans thread is closed and everyone posts on the autumn thread instead when the weather is usually blazing sunshine, insects are still buzzing about and the trees are still in full leaf. Considering the leaves don’t usually start falling off the trees until October, September doesn’t really seem like an autumn month to me. Yes, the weather can be autumnal at times, especially during the second half of the month, but the first half of the month more often than not just feels like a continuation of summer. Also the fact that Autumn is called “fall” in America because it’s the season when the leaves start falling, it doesn’t really make sense to say it’s autumn in September before the leaves have even started falling. Astronomically Autumn doesn’t start until 21st September anyway.

 

I also think maybe December should be classed as an autumn month now considering it’s usually mild, wet and windy rather than very cold.

I realise I might have jinxed this September and it might turn out to be a cool, wet and autumnal month!

 

Edited August 16 by East Lancs Rain

[MP-R]

Summer is as much about day length and sun strength as temperature, so in a word, no.

Although from time to time the first half of the month can mimic summer like March can winter.

[I remember Atlantic 252]

Yes, even though holidays are over, but maybe not in Scotland as holidays over earlier

[damianslaw]

No, September is firmly autumnal, its a long way since the summer solstice, light levels are dropping markedly, sun strength weakens markedly, it coincides with the autumn equinox, nature takes on autumnal change - migration etc. Yes it can and often does start off summery like weatherwise, but as a whole it is not summer. 30th September feels a far cry from 1 June. 

Edited August 16 by damianslaw

[LetItSnow]

The stats show it's wetter and with much less sunshine plus for all the heat September can deliver it can also deliver sharp frosts and Atlantic gales. June can bring the frosts in rare severe northerlies but is much less likely to bring the wet and windy weather. Plus daylight is lost rapidly, so, no, I don't think so.

Edited August 16 by LetItSnow

[I remember Atlantic 252]

 damianslaw for northern members maybe not, May often more summer than Sept

[Jon Somerset]

I follow astronomical rather than meteorological seasons as they make much more sense to me. So the solstices and equinoxes are the season changes. So autumn starts late September and carries in to mid-December and so on.

[Don]

I would say no as even when it's very warm or hot, it feels different from mid July to mid August!

[I remember Atlantic 252]

My birthday is on average more summer than autumn, been lucky really and always holidays

[IcySpicy]

In Estonia definitely not, although we've had a few rare years where September has a higher average temp than June. Still, the second half of the month is usually quite chilly already and the changes in daylight and foliage make it feel different from summer. I don't consider May summer either as the start of the month is often still cold and trees are just starting to leaf out even though sun strength is similar to mid July-early August. 

I do sometimes think of November and March as winter months though, especially if they are cold and snowy haha.

[Glaswegianblizzard]

I think early September should be, just as early March could be considered winter here

[Alexis]

Whilst September usually has a summery spell, and it's happening more often, it's still usual to get a first frost in Scotland.

I don't think any month can be classed as summer if a frost is normal.

[sunny_vale]

I see May to September as the extended summer period really - May has the light and September has the warmth and is often very settled 

[Weather Enthusiast91]

I don't think so, no. Despite what the temperature may be, nature (ie; trees shedding their leaves and an increase in mist and fog), sun strength and loss of daylight hours makes it very much an autumn month, albeit early autumn. And September is actually rarely warmer than August. Since 1974, only three Septembers had higher CETs than their preceding Augusts.

 

Edited August 16 by Weather Enthusiast91

[WYorksWeather]

I think we already have a perfectly useful definition for May and September which is often used in weather / climate circles - the extended warm season. It's not summer, but any time from May to September can produce summer-like conditions in terms of heatwaves / heat spikes, or more consistent benign warm / very warm weather, etc. I'd probably set it out like this.

I would say that high summer / core summer runs from around the start of July to the middle of August. This is usually when the hottest day of the year is recorded.

You then add on June and the second half of August to make up the meteorological summer, which is the warmest three month period overall, but the warm spells outside of high summer are less likely to be very hot or challenge records. Still, generally a reliably warm time of year.

Around that, you then have the extended warm season, when summer-like conditions are still possible, but with something of a different feel than during the meteorological summer, due to either the cold seas and chilly nights (May) or the cloudier and mistier conditions and shorter days (September). I still value warm weather at these times of year, but it is definitely different to warm weather during the actual summer.

 

[TheOgre]

I think you can make a case for the pre equinox period being summer, yes, especially near a coastal area with seasonal lag. The warmest quarter of the year even in my location is from around 10 June to 10 September. Post equinox, hard no as the nights are longer than the days and on average it’s starting to get as cool as May.

Around 10 June to 10 September could be seen as thermal summer with dates varying from location to location.

[summer blizzard]

We would need see the data but I suspect that Maxima in September is typically lower than June (assume warmer than May) which coupled with declining sun strength and longer nights means that unless it's a 15C+ month, it arguably does not feel like summer. 

The second half of the month especially can start to feel pretty autumnal when it's not settled and warm.

[WYorksWeather]

 summer blizzard Seasonal lag means that September is warmer than May just about everywhere. It is cooler than June though in almost every case.

Perhaps the only way in which September can be argued to be on a par with June is the upper end for temperatures. The June record of 35.6C from 1976 at Southampton Mayflower Park is exactly equal to the September record set in 1906 at Bawtry Hall.

Overall though, in terms of consistent warmth, September is clearly not on a par with June, even if you roll the clock back to 1961-1990. I remember looking at this a while ago and the only month that has truly warmed enough to actually be considered part of the adjacent season (at least from a temperature perspective) is February, in the sense that the last 10 Februaries have averaged as warm as a 1961-1990 March.

[stainesbloke]

In Czechia, September is often summery up to the equinox, then there’s quite a noticeable change. I’d also class March as winter up to the equinox as it’s rarely spring-like before then. 

[Wold Topper]

To answer the original question, i personally don't care, we follow a calendar that is predetermined and the weather will do as it pleases, the two aren't connected, to think it all fits in nice tidy boxes of equal proportions is absurd.

[Dark Horse]

 East Lancs Rain a good chunk of December 2022 was very chilly. Not much snow for most but coldest December since 2010. I think because there wasn't widespread snow it's one of those forgotten cold months a bit like Feb 86. I had my weather station back then in Dec 22 and I recorded 9 consecutive ice days on the trot. Not bad in this day and age. Below is the airport.

 

 

 

 

[Earthshine]

I think so.  September feels very summery here, perhaps the very end of the month feeling more autumnal with sunset before 7 pm.  However even October can feel very summery, the picture below is from my commute home in early October last year when it was 24°C.  24°C is warmer than the mean maximum for July!

[laddie]

Apart from darker mornings and evenings, daytime's certainly an extension to summer locally,  I used to always go camping on the Norfolk coast in September and don't recall having any bad weather 

[SunSean]

September has always been Summer lol (The 1st half anyway). Astronomical Summer (which is more accurate since meteorological seasons are more used for convenience) normally begins on June 21st til September 22nd but I'd say Mid June to Mid September is Summer time with Mid August to Mid September being late Summer.

1st half of June average max here- 20.8c

1st half of September average max- 21.5c

Been down the beach many a time in early September and it's felt like nothing other than Summer!

[RJBingham]

  Definitely , often the best summer month too.