Mild September = A Mild Winter?

[In Absence of True Seasons]

 Derecho Or literally any month of the year impacting how the weather 2/3/4 months away with manifest.

A warm June = a warm rest of summer? Nope. 2023

A warm late Winter = a warm Spring. Nope. Again, 2023.

A cold late winter = a cold Spring. Nope. 2018 with beast from the East for example. Then in April (in my area anyway), we had 20c+ sunny days. 

So on and so forth.

[baddie]

September 2015 was 2c colder than average but lead to the mildest winter ever. Same thing for September 2013 and 2018
September 2005 was warmer than average and lead to a cold extended winter. Same with 2009
 

[sundog]

At the end of the day anyone wrote off this winter back in September wasn't exactly wrong.  Despite some of the factors favouring a decent winter. The models , teleconnections and some ramping that went along with it. I thought this winter would be rubbish anyway regardless of September due to El Niño. But the very warm September made me even more convinced.  Though even I got  a bit sucked into some of the charts and rampings earlier in the winter.  Thinking  maybe I might be surprised. Nope should have listened to my original thinking. 

Edited February 17 by sundog

[The PIT]

If December averages 6C or more you are extremely unlikely to see a cold winter with following months more likely to be also mild or at worst average.

[North-Easterly Blast]

 The PIT In recent times after mild Decembers the rest of the winter has never got colder, but further back in the past there are various years where the rest of the winter has actually turned much colder after a mild December.  A few of these that I can think of are 1900-01 (Dec 7.2 Jan 3.5 Feb 2.3), 1918-19 (Dec 6.9, Jan 2.9, Feb 1.9), 1953-54 (Dec 6.9, Jan 2.9, Feb 2.6), 1954-55 (Dec 6.8, Jan 2.6, Feb 1.2).  Back in the 1800s other examples could be 1857-58 (Dec 7.3, Jan 3.4, Feb 1.8), 1852-53 (Dec 7.7, Jan 5.1, Feb 0.6), 1843-44 (Dec 7.4, Jan 3.8, Feb 1.6), 1842-43 (Dec 7.2, Jan 4.0, Feb 1.9).  

The most recent examples that I could think of for winters that had a pretty mild December followed by a much colder rest of the winter is 1985-86 (Dec 6.3, Jan 3.5, Feb -1.1) and 1986-87 (Dec 6.2, Jan 0.8, Feb 3.6). 

Although there have been very mild Decembers where the rest of the winter has remained mild, like 1988-89, and occasional very mild Decembers with the rest of the winter turning less mild but not cold, like 2015-16, and to some extent 1974-75, as the February of that winter fell back closer to average though not cold, though that said March 1975 was below average, particularly with quite a cold spell later on in that month that did deliver some snow to some parts of the country.

Edited February 17 by North-Easterly Blast