Since this didn't belong in any other topic I know of, I thought it prudent to create a new one. Basically this thread will catalogue and discuss the seasonal lags of climates worldwide. For those who are so inclined we can even throw in some fantasy climates.
Nei may beg to differ

, but I consider the standard seasonal pattern to be this:
January is the coldest month
July is the hottest month
February is the same as December, March is the same as November, October is the same as April, et cetera
The true seasonal lag is the lag in heating between land or sea and the strength of the sun. This would be a bit complex to figure out, not to mention putting all of Earth in a lagging state, so I concocted this "standard model". Although it may not be the most common pattern, I think this is the one that should be used in our calculations here, since it is easy to figure out the difference in mean temperature between October and April (simple subtraction), whereas a maritime baseline would be more complex. It also enables us to pick out the leading climates that follow the temperature of the land from the lagging climates that follow the temperature of the sea.
To figure out the seasonal lag of a place, one takes the mean temperature of a given spring month, and subtracts it by the mean temperature of its equivalent autumn month (example: April Mean minus October mean). One has a seasonal lag figure. If there is a lag it will show up as a negative number. Since we're cataloging lagging here, it would be advisable to flip the signs, so that a lag is positive and a lead is negative, i.e. greater lags show up as greater numbers. Since January and July are their own equivalents on the calendar in this model, there can be no figures for them.
The results of this prove interesting, and reveal how "laggy" a climate is.
I have already done this for a few cities. A lag is a positive number and a lead is a negative number:
New York, New York:
Feb-Dec: +2.25F
Mar-Nov: +5.25F
Apr-Oct: +3.9F
May-Sep: +5.6F
Jun-Aug: +3.8F
Nashville, Tennessee:
Feb-Dec: -1.3F
Mar-Nov: -0.2F
Apr-Oct: +1.3F
May-Sep: +4F
Jun-Aug: +3F
Fairbanks, Alaska:
Feb-Dec: -2.15F
Mar-Nov: -8.85F
Apr-Oct: -8.2F
May-Sep: -4.25F
Jun-Aug: -3.45F
Chicago, Illinois:
Feb-Dec: -0.1F
Mar-Nov: +2.5F
Apr-Oct: +3.7F
May-Sep: +5.6F
Jun-Aug: +3.15F
Urumqui, Uyghyr Autonomous Region, China:
Feb-Dec: +1.05F
Mar-Nov: -1.1F
Apr-Oct: -4.1F
May-Sep: 0F
Jun-Aug: +1.8F
And for kicks, my fictitious dream climate:
Feb-Dec: -0.7F
Mar-Nov: -0.2F
Apr-Oct: -3.7F
May-Sep: -3.3F
Jun-Aug: -1F
I'd like for us here to post lag figures for real-world climates, and I'd like for posters here to do the math for their fantasy climates. The differences should be interesting

.
There is something more or less related to this called the Index of Oceanicity. It was developed by someone named Kerner if I'm not mistaken. The formula is as follows:
Oceanicity = 100((T
Oct-T
Apr)/(T
Range))
The T
Oct is the mean temperature for October in degrees Celsius, and the T
Apr is the same for April. T
Range is the difference between the means of the hottest and coldest months in degrees Celsius.
If you're so inclined, you can copy the right side of the equation, and if you plug in the relevant numbers Google or WolframAlpha can calculate it.
The results of this formula applied to the cities mentioned above are likewise interesting. Below are the oceanicity index figures for them:
New York City: +8.81
Nashville: +3.02
Fairbanks: -23.06
Chicago: +7.13
Urumqui: -6.36
My dream climate: -6.29
I would appreciate any additional input. Mean temperatures aren't the only thing one can profile. The occurrence of atypical heat waves or cold snaps over the course of a year can be another metric. A shining example of this would be
Whitehorse. Although mean temperatures don't display this much of a lead, the second-hottest temperature ever recorded occurred in the month of
May. The hottest ever recorded occurred in June, and July and August's record highs come in third and fourth, respectively. A lesser example of this would be the difference between springtime record highs of
Nashville and
New York. Despite averaging 10F warmer in April, Nashville's monthly record high of 91F falls short of NYC's record of 96F.