Why do the Southern and Central regions of the US Midwest exhibit seasonal lag in Spring/Early Summer? (climate, warmest)

[alex985]

......but a seasonal lead in late Autumn and early Winter? It's a very peculiar pattern. Also, I noticed this pattern wanes when you reach the Upper Midwest. For example:



Kansas City, MO:

Difference in temps Feb-June: 40.0 F (22.2 C)

Difference in temps Aug-Dec: 45.6 F (25.3 C)

Average mean temp Apr-June: 64.3 F (17.9 C)

Average mean temp Aug-October: 67.2 F (19.6 C)

Difference: 2.9 F (1.6 C)

Average mean temp Feb-March: 39.0 F (3.9 C)

Average mean temp Nov-Dec: 37.5 F (3.1 C)

Difference: -1.5 F (-0.8 C)

Temperature drop Oct-Dec: 24.9 F (13.8 C)

Temperature rise Apr-June: 18.8 F (10.4 C)

Kansas City, Missouri - Wikipedia, the free encyclopedia

Pattern is still in place in Omaha, NE; about 200 miles up the road:

Difference in temps Feb-June: 44.0 F (24.4 C)

Difference in temps Aug-Dec: 48.6 F (27.0 C)

Average mean temp Apr-June: 62.1 F (16.7 C)

Average mean temp Aug-Oct: 64.5 F (18.1 C)

Difference: 2.4 F (1.3 C)

Average mean Feb-March: 33.8 F (1.0 C)

Average mean Nov-Dec: 32.4 F (0.2 C)

Difference: -1.4 F (0.8 C)

Temperature drop Oct-Dec: 27.2 F (15.1 C)

Temperature rise Apr-June: 20.3 F (11.3 C)

Omaha, Nebraska - Wikipedia, the free encyclopedia

Another 200 miles up the road, same pattern is set up in Sioux Falls, SD:

Difference in temps Feb-June: 46.3 F (25.7 C)

Difference in temps Aug-Dec: 51.6 F (28.7 C)

Average mean temp Apr-June: 57.4 F (14.2 C)

Average mean temp Aug-Oct: 59.8 F (15.4 C)

Difference: 2.4 F (1.3 C)

Average mean temp Feb-March: 27.2 F (-2.7 C)

Average mean temp Nov-Dec: 25.4 F (-3.8 C)

Difference: -1.8 F (1.0 C)

Temperature rise Apr-June: 21.3 F (11.8 C)

Temperature drop Oct- Dec: 29.2 F (16.2 C)


Sioux Falls, South Dakota - Wikipedia, the free encyclopedia

Another 200 miles up the road in Fargo, ND, the difference starts to wane a bit, as Sept-Oct become closer in mean temps to Apr-May:

Temperature rise Feb-June: 51.6 F (28.7 C)

Temperature drop Aug-Dec: 55.1 F (30.6 C)

Average mean temps Apr-June: 55.7 F (13.2 C)

Average mean temps Aug-Oct: 57.9 F (14.4 C)

Difference: 2.2 F (1.2 C)

Average mean temps Feb-March: 21.3 F (-5.9 C)

Average mean temps Nov-Dec: 21.5 F (-5.8 C)

Difference: 0.2 F (0.1 C)

Temperature rise Apr-June: 22.4 F (12.4 C)

Temperature drop Oct-Dec: 31.4 F (17.4 C)

Fargo, North Dakota - Wikipedia, the free encyclopedia

I wonder what causes this pattern? One hypothesis I have is that since Spring is the peak of Severe Weather season and also the wettest months in these cities, maybe that hinders the warm-up a bit and stops ridges of high pressure from building, while the reverse is true Aug-Oct (much drier than Apr-June, so maybe it's more likely for ridges to build in the Midwest during this period)?

[Thunder98]

[alex985]

Not sure how that answers my question, but it's an interesting map nonetheless.

[Thunder98]

Here's the coldest day of the year.