Whilst the article is interesting, the knowledge of climate history I have gathered always appears to say that the period of the Great Depression from 1928/1929 to 1936/1937 saw winters as unusual —both in warmth and cold — as the period under review. An earlier analysis I did a year or two ago did not suggest this. This applies even when the two periods are analysed region by region. This last step is very important since I have long noted that many Depression winters saw extreme but opposite sign temperature anomalies in the West and East (and also in Alaska, which under stable global temperatures forms a three-way seesaw with the two contiguous regions). I also noticed studying the article that there was a remarkable absence of extreme winters in the contiguous United States between 1954/1955 and 1974/1975. During these twenty-one years, not one winter was outside 1.179 standard deviations from the mean — an occurrence with probability under 0.2 percent. This is noticed briefly also in ‘Agriculture and the Recent “Benign Climate” in Minnesota’ by Donald G. Baker, David L. Ruschy and Richard H. Skaggs.
As an extension of ‘Recent Unusual Mean Winter Temperatures Across the Contiguous United States’, I have attempted to do an analysis of CONUS temperatures over the extended winter seasons from November to March and from October to March, using the same criteria found in the original study. Karl, Livezey and Epstein showed that a departure of 1.253 standard deviations from the CONUS-averaged mean qualifies a season as “abnormal” in that the proportion of a normal distribution outside such a range is less than one-tenth the complete set of data. However, they also noted a range of 1.179 standard deviations from the mean to give a slightly less rigid definition of an “unusual” season. With this noted, I will analyse the extended winter seasons to see if they produced the same abnormalities Karl, Livezey and Epstein noticed for the December to February season.
November to March:
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| Mean area-averaged contiguous US temperature from November to March between 1895/1896 and 1983/1984, with mean shown with dashed line and 1.179 standard deviations above and below mean with solid line |
| Year | Contiguous U.S. Average T, November to March (˚C) | Standardised anomaly |
| 1895/1896 | 1.71 | -0.46 |
| 1896/1897 | 1.58 | -0.64 |
| 1897/1898 | 2.08 | +0.06 |
| 1898/1899 | -0.02 | -2.84 |
| 1899/1900 | 2.52 | +0.66 |
| 1900/1901 | 2.02 | -0.03 |
| 1901/1902 | 1.81 | -0.33 |
| 1902/1903 | 1.77 | -0.37 |
| 1903/1904 | 1.29 | -1.03 |
| 1904/1905 | 1.59 | -0.63 |
| 1905/1906 | 1.77 | -0.38 |
| 1906/1907 | 3.03 | +1.36 |
| 1907/1908 | 2.76 | +0.99 |
| 1908/1909 | 2.61 | +0.78 |
| 1909/1910 | 2.11 | +0.09 |
| 1910/1911 | 2.63 | +0.81 |
| 1911/1912 | 0.12 | -2.66 |
| 1912/1913 | 1.53 | -0.70 |
| 1913/1914 | 2.58 | +0.74 |
| 1914/1915 | 1.28 | -1.05 |
| 1915/1916 | 2.18 | +0.19 |
| 1916/1917 | 0.65 | -1.92 |
| 1917/1918 | 1.84 | -0.27 |
| 1918/1919 | 2.21 | +0.23 |
| 1919/1920 | 1.26 | -1.09 |
| 1920/1921 | 3.41 | +1.89 |
| 1921/1922 | 1.87 | -0.24 |
| 1922/1923 | 1.98 | -0.08 |
| 1923/1924 | 1.91 | -0.18 |
| 1924/1925 | 2.40 | +0.49 |
| 1925/1926 | 2.28 | +0.33 |
| 1926/1927 | 2.61 | +0.78 |
| 1927/1928 | 2.44 | +0.55 |
| 1928/1929 | 1.26 | -1.09 |
| 1929/1930 | 1.82 | -0.30 |
| 1930/1931 | 2.51 | +0.65 |
| 1931/1932 | 2.67 | +0.87 |
| 1932/1933 | 1.77 | -0.38 |
| 1933/1934 | 3.46 | +1.95 |
| 1934/1935 | 3.20 | +1.60 |
| 1935/1936 | 0.69 | -1.86 |
| 1936/1937 | 1.08 | -1.33 |
| 1937/1938 | 2.96 | +1.27 |
| 1938/1939 | 2.28 | +0.33 |
| 1939/1940 | 2.13 | +0.13 |
| 1940/1941 | 2.22 | +0.24 |
| 1941/1942 | 2.32 | +0.39 |
| 1942/1943 | 2.26 | +0.29 |
| 1943/1944 | 2.06 | +0.02 |
| 1944/1945 | 2.61 | +0.78 |
| 1945/1946 | 2.68 | +0.88 |
| 1946/1947 | 2.21 | +0.23 |
| 1947/1948 | 1.03 | -1.40 |
| 1948/1949 | 1.42 | -0.86 |
| 1949/1950 | 2.59 | +0.76 |
| 1950/1951 | 1.88 | -0.23 |
| 1951/1952 | 1.61 | -0.60 |
| 1952/1953 | 3.27 | +1.69 |
| 1953/1954 | 3.24 | +1.65 |
| 1954/1955 | 2.05 | +0.01 |
| 1955/1956 | 1.55 | -0.68 |
| 1956/1957 | 2.55 | +0.70 |
| 1957/1958 | 2.06 | +0.02 |
| 1958/1959 | 2.07 | +0.04 |
| 1959/1960 | 1.17 | -1.21 |
| 1960/1961 | 2.63 | +0.82 |
| 1961/1962 | 1.26 | -1.08 |
| 1962/1963 | 2.09 | +0.07 |
| 1963/1964 | 1.56 | -0.66 |
| 1964/1965 | 1.57 | -0.65 |
| 1965/1966 | 2.34 | +0.42 |
| 1966/1967 | 2.83 | +1.09 |
| 1967/1968 | 2.12 | +0.10 |
| 1968/1969 | 1.04 | -1.38 |
| 1969/1970 | 1.78 | -0.36 |
| 1970/1971 | 1.94 | -0.14 |
| 1971/1972 | 2.57 | +0.72 |
| 1972/1973 | 1.81 | -0.33 |
| 1973/1974 | 2.97 | +1.28 |
| 1974/1975 | 2.21 | +0.23 |
| 1975/1976 | 3.19 | +1.58 |
| 1976/1977 | 1.30 | -1.02 |
| 1977/1978 | 1.25 | -1.09 |
| 1978/1979 | 0.38 | -2.30 |
| 1979/1980 | 2.14 | +0.14 |
| 1980/1981 | 3.26 | +1.68 |
| 1981/1982 | 2.13 | +0.13 |
| 1982/1983 | 3.26 | +1.67 |
| 1983/1984 | 1.64 | -0.55 |
October to March:
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| Mean area-averaged contiguous US temperature from October to March between 1895/1896 and 1983/1984, with mean shown with dashed line and 1.179 standard deviations above and below mean with solid line |
| Year | Contiguous U.S. Average T, October to March (˚C) | Standardised anomaly |
| 1895/1896 | 3.17 | -0.87 |
| 1896/1897 | 3.16 | -0.89 |
| 1897/1898 | 3.87 | +0.19 |
| 1898/1899 | 1.79 | -2.98 |
| 1899/1900 | 4.13 | +0.59 |
| 1900/1901 | 3.94 | +0.30 |
| 1901/1902 | 3.67 | -0.11 |
| 1902/1903 | 3.56 | -0.29 |
| 1903/1904 | 3.11 | -0.97 |
| 1904/1905 | 3.36 | -0.59 |
| 1905/1906 | 3.29 | -0.69 |
| 1906/1907 | 4.43 | +1.04 |
| 1907/1908 | 4.32 | +0.87 |
| 1908/1909 | 4.01 | +0.40 |
| 1909/1910 | 3.69 | -0.08 |
| 1910/1911 | 4.37 | +0.96 |
| 1911/1912 | 2.01 | -2.64 |
| 1912/1913 | 3.24 | -0.77 |
| 1913/1914 | 3.97 | +0.34 |
| 1914/1915 | 3.22 | -0.81 |
| 1915/1916 | 3.98 | +0.36 |
| 1916/1917 | 2.41 | -2.04 |
| 1917/1918 | 3.24 | -0.77 |
| 1918/1919 | 4.08 | +0.52 |
| 1919/1920 | 2.95 | -1.21 |
| 1920/1921 | 4.94 | +1.82 |
| 1921/1922 | 3.72 | -0.04 |
| 1922/1923 | 3.78 | +0.06 |
| 1923/1924 | 3.37 | -0.57 |
| 1924/1925 | 4.13 | +0.58 |
| 1925/1926 | 3.47 | -0.42 |
| 1926/1927 | 4.30 | +0.85 |
| 1927/1928 | 4.25 | +0.77 |
| 1928/1929 | 3.18 | -0.86 |
| 1929/1930 | 3.55 | -0.30 |
| 1930/1931 | 3.92 | +0.26 |
| 1931/1932 | 4.50 | +1.15 |
| 1932/1933 | 3.35 | -0.60 |
| 1933/1934 | 5.03 | +1.96 |
| 1934/1935 | 4.94 | +1.82 |
| 1935/1936 | 2.59 | -1.75 |
| 1936/1937 | 2.89 | -1.31 |
| 1937/1938 | 4.49 | +1.14 |
| 1938/1939 | 4.16 | +0.64 |
| 1939/1940 | 3.88 | +0.20 |
| 1940/1941 | 4.08 | +0.51 |
| 1941/1942 | 4.08 | +0.52 |
| 1942/1943 | 3.97 | +0.34 |
| 1943/1944 | 3.72 | -0.03 |
| 1944/1945 | 4.33 | +0.89 |
| 1945/1946 | 4.28 | +0.81 |
| 1946/1947 | 3.80 | +0.08 |
| 1947/1948 | 3.34 | -0.62 |
| 1948/1949 | 3.14 | -0.92 |
| 1949/1950 | 4.20 | +0.69 |
| 1950/1951 | 3.92 | +0.27 |
| 1951/1952 | 3.37 | -0.57 |
| 1952/1953 | 4.66 | +1.40 |
| 1953/1954 | 4.94 | +1.82 |
| 1954/1955 | 3.81 | +0.09 |
| 1955/1956 | 3.42 | -0.49 |
| 1956/1957 | 4.36 | +0.94 |
| 1957/1958 | 3.53 | -0.32 |
| 1958/1959 | 3.83 | +0.14 |
| 1959/1960 | 2.94 | -1.22 |
| 1960/1961 | 4.30 | +0.85 |
| 1961/1962 | 3.07 | -1.03 |
| 1962/1963 | 3.98 | +0.36 |
| 1963/1964 | 3.83 | +0.14 |
| 1964/1965 | 3.33 | -0.64 |
| 1965/1966 | 4.08 | +0.52 |
| 1966/1967 | 4.29 | +0.83 |
| 1967/1968 | 3.79 | +0.07 |
| 1968/1969 | 2.97 | -1.19 |
| 1969/1970 | 3.25 | -0.75 |
| 1970/1971 | 3.49 | -0.39 |
| 1971/1972 | 4.28 | +0.81 |
| 1972/1973 | 3.38 | -0.55 |
| 1973/1974 | 4.71 | +1.47 |
| 1974/1975 | 3.86 | +0.18 |
| 1975/1976 | 4.75 | +1.53 |
| 1976/1977 | 2.74 | -1.53 |
| 1977/1978 | 3.08 | -1.02 |
| 1978/1979 | 2.39 | -2.07 |
| 1979/1980 | 3.94 | +0.30 |
| 1980/1981 | 4.62 | +1.34 |
| 1981/1982 | 3.66 | -0.13 |
| 1982/1983 | 4.68 | +1.43 |
| 1983/1984 | 3.50 | -0.37 |
Analysis and Conclusions:
The tables above suggest that, when we extend the winter season to November to March, and to October to March, we find that the period from 1975/1976 to 1983/1984 was not so unusual as Karl, Livezey and Epstein suggested. Only four of the nine November to March periods were outside the range described in their article, and only five of the nine October to March periods.
We also find that the period from 1954/1955 to 1974/1975 was not so exceptional for lacking extremes when we extend the winter season. Based on a November to March or an October to March period, 1959/1960 and 1968/1969 were “unusually” cold, and 1973/1974 unusually warm, though 1959/1960 is a marginal case on both periods, and October 1968 to March 1969 is likewise. 1973/1974, though, is especially warm in the Deep South, where January 1974 remains the warmest on record in South Carolina, Georgia and Florida.
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| Standardized contiguous US temperature anomalies relative to 1895 to 2000 mean for October 1959 to March 1960. Note area in southeastern Nebraska and northern Kansas over two standard deviations below the mean, and extensive area in West South Central and Plains colder than 1.5 standard deviations below the mean |
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| Standardized contiguous US temperature anomalies relative to 1895 to 2000 mean for October 1973 to March 1974. Note wide area of the South hotter than 1.5 standard deviations above average. |
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| Standardized contiguous US temperature anomalies relative to 1895 to 2000 mean for November 1968 to March 1969. Note widespread area colder than 1.5 standard deviations below mean from Florida to Montana |
We can also note that the winter of 1981/1982 is slightly above normal when measured on the basis of November to March, and only slightly below on an October to March basis. This is because November 1981 was from coast to coast the hottest since 1949 and at the time the sixth-hottest since 1895. Over Minnesota it was the warmest since 1899, over North Dakota the warmest since 1949, and over South Dakota and Nebraska the warmest since 1954, although Monthly Weather Review failed to hint at this via reference to long-term stations there.
The very long Fort Snelling, Minnesota record — the oldest temperature station west of the Appalachian Mountains — shows November 1830 and November 1849 as over 1˚C warmer than any November during the twentieth century, not being exceeded until November 2001 when Australian coal barons and Gulf oil sheikhs had taken firm control of the climate. Nonetheless, November 1981 was relative to the preindustrial mean more abnormally warm over the contiguous US overall than January 1982 was cold, so it makes sense that the extended 1981/1982 winter was not cold.
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| November CONUS temperature from 1895 to 1997, with 1895 to 1974 mean of 41.54˚F or 5.3˚C. Note November 1981’s warmth, previously exceeded only by Novembers 1949, 1934, 1913, 1909 and 1899 |
The very long Fort Snelling, Minnesota record — the oldest temperature station west of the Appalachian Mountains — shows November 1830 and November 1849 as over 1˚C warmer than any November during the twentieth century, not being exceeded until November 2001 when Australian coal barons and Gulf oil sheikhs had taken firm control of the climate. Nonetheless, November 1981 was relative to the preindustrial mean more abnormally warm over the contiguous US overall than January 1982 was cold, so it makes sense that the extended 1981/1982 winter was not cold.
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| Standardised mean temperature anomalies by climate division over the contiguous US for November 1981. Note the anomalous warmth in the Great Plains and Minnesota (where it was the warmest for 82 years) |
The very cold winter of 1977/1978 also appears less abnormal when measured over the extended winter, again largely due to a relatively warm November (though not nearly so warm as November 1981). 1976/1977 is affected by a very warm March, which would lead into the hottest spring/summer season from coast to coast since 1936 (ironically, also the last colder winter!). The winter of 1947/1948, on a November to March basis, also stands out as abnormally cold. [1947/1948 is not exceptional on an October to March basis since October 1947 was exceptionally hot — the hottest by mean minimum temperature of the century, and the second-hottest by mean temperature.]
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| Standardised divisional temperature anomalies for the period from November 1947 to March 1948. Note the general cold outside of Florida, and the area in the Southwest colder than two standard deviations below the mean |
The Depression Era:
An earlier cursory examination, and basic knowledge of contiguous US temperature maps, has made me suggest that the winters discussed by Karl, Livezey and Epstein for the Carter and early Reagan eras were replicated during the Great Depression. The table on page 1304 notes several abnormal winters in the Depression era in 1930/1931 (marginal), 1931/1932, 1933/1934 and 1935/1936. However, at a local divisional level, it is clear that almost all the winters from 1928/1929 to 1936/1937 were highly abnormal. The exceptions I noted were 1929/1930 and 1934/1935, but the former is practically disqualified, for it saw a record cold January followed by a record warm February.The tables above, however, do show that the extended winters during the 1930s were in fact more abnormal than those of the late 1970s and early 1980s. Five consecutive years from 1933/1934 to 1937/1938 qualify as abnormal based on November to March temperature, and the first four are also abnormal based upon October to March temperature. 1934/1935 is particularly striking despite the winter’s apparent absence of large regional anomalies: in fact it is the equal second-warmest October to March between at least 1883 and 1991:
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| Standardised divisional anomalies for October 1934 to March 1935. Note departures exceeding plus two standard deviations in Southern Plains, and 2.5 standard deviations in division OK 1 |
In fact, in climate divisions OK 1 [Cimarron, Texas, Beaver, Harper and Ellis Counties], and KS 7 [Southwest], this was the warmest October to March period until 2016:
For Oklahoma as a whole, 1934/1935 was the warmest October to March until 2000. The extended winter of 1936/1937 featured not merely a record cold January west of the Mississippi, but also general cold in October, November and March. 1937/1938, although only marginal for the list above, and not qualifying by an October to March period at all, was warmer than normal virtually everywhere and substantially so in the South and the Intermountain West:
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| Divisional monthly mean temperature standardised anomalies relative to 1895 to 2000 mean for November 1937 to March 1938. Note striking absence of cooler than average areas |
Thus, this study shows my suspicion that Great Depression-era winters were just as abnormal as those of the late 1970s and early 1980s to be correct. This becomes emphatically true when one observes the extreme regional divides found in several of the early 1930s, and the extreme contrast between then-record cold January 1930 and then-record warm February 1930. All these contrasts were noted eleven years ago here.
Beyond Climate Division Era — A Possible Analogue in the Post-Reconstruction Years:
Some time ago, looking to expand knowledge of US climate history beyond the GISS temperature maps (which go back to 1880), I noticed a possible parallel — at least over the Midwest — between approximately 1875 and 1890. Studying the data for Dubuque, Iowa — where temperature data go back to 1851, or twenty years further than most of the US outside the Northeast — I noticed a large number of abnormal winters during those post-Reconstruction years. I observed especially how six of the twelve warmest winters in Dubuque between 1851 and 1975 occurred in this era:
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| Mean winter temperature in Dubuque, Iowa from 1851/1852 to 1983/1984 [later year labelled on x-axis], with -1.179σ and +1.179σ marked by solid lines, and all-series mean to 1984 by dashed line. |
The graph does show a very clear concentration of abnormal winters between 1875 and 1890. Although a comparison with Fort Snelling, Minnesota suggests the Dubuque shelters in use at this time may have given hotter temperatures than a standard modern shelter, this does not refute the argument for an unusual concentration of abnormal Midwestern winters in the late 1870s and 1880s, and the stark contrast with the 1860s. If we extend the winter seasons for Dubuque as we did in the first experiment in this post, we find that the abnormality of post-Reconstruction winters largely remains, although the warm seasons from 1888/1889 to 1891/1892 become fairly unexceptional:
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| Mean November to March temperature in Dubuque, Iowa from 1851/1852 to 1983/1984 [later year labelled on x-axis], with -1.179σ and +1.179σ marked by solid lines, and all-series mean to 1984 by dashed line. |
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| Mean November to March temperature in Dubuque, Iowa from 1851/1852 to 1983/1984 [later year labelled on x-axis], with -1.179σ and +1.179σ marked by solid lines, and all-series mean to 1984 by dashed line. |
Despite the unexceptional nature of the seasons from 1888/1889 to 1891/1892, there remains a sufficient number of abnormal winters in the 1870s and 1880s to make the “exceptional” period a century later seem much less so. It is unfortunate that for the western half of the United States too few temperature data exist to discover whether the contrast between an absence of extreme winters in the 1860s and an abundance thereof in the 1870s and 1880s was replicated there. Data from Boise, Idaho — the oldest station in the Northwest — suggest that:
- the winters of the late 1870s and 1880s were less abnormal than in the Midwest, and most are unlikely to be abnormal except when the extended season is used
- the winters of the 1930s and from the middle 1970s to the middle 1980s were exceptionally abnormal in this region of the United States
