Central England temperature
The Central England Temperature (CET) record was originally published by Professor Gordon Manley in 1953 and subsequently extended and updated in 1974, following many decades of painstaking work. The monthly average surface air temperatures, for the Midlands region of England, are given (in degrees Celsius) from the year 1659 to the present.
This record represents the longest accurate series of monthly temperature observations in existence. It is an extremely valuable dataset for meteorologists and climate scientists. It is monthly from 1659, and a daily version has been produced from 1772. The monthly means from November 1722 onwards are given to a precision of 0.1°C. The earliest years of the series, from 1659 to October 1722 inclusive, for the most part only have monthly means given to the nearest degree or half a degree, though there is a small 'window' of 0.1 degree precision from 1699 to 1706 inclusive. This reflects the number, accuracy, reliability and geographical spread of the temperature records that were available for the years in question.
Trends Revealed by the Series
The series is useful to climate researchers because the trends in temperatures since the mid-17th century can be followed. It shows that temperatures fell during the period roughly 1650-1700 and then rose sharply in the early 1700s. During the 18th and 19th centuries, a cool period which coincided with snowy winters and generally cool summers, the temperatures fluctuated widely but with little trend. From 1910, temperatures increased slightly until about 1950 when they flattened before a sharp rising trend began in about 1975. Temperatures so far in the current decade (years 2001-2008) are remarkably different in all seasons from the long-term average.<ref> CET Data; Mean annual temperature for 2001 to 2007 is 10.49°C compared to warmest decade of 20th century, -the 1990s- 10.06°C, and the warmest decade of the period 1659 to 1900 -the 1730s- 9.54°</ref>
For recent years there are two versions of the series: the "official" version maintained by the Hadley Centre for Climate Prediction and Research, and a version maintained by Philip Eden which he argues is more consistent with the series as originally compiled by Manley.<ref>Checking the CET</ref>
Taking the 350 year period for the series as a whole:
- The hottest year in the sequence was 2006 with a mean temperature of 10.82°C, a notable jump on the previous record, a tie between 1990 and 1999 with a mean of 10.63°C<ref>2006 sets British heat records, BBC News, Thursday, 14 December 2006</ref>
- The warmest spring (March, April, May) was in 1893 with a mean of 10.20°C, breaking the previous record of 9.73°C set in 1779.
- The hottest summer (June, July, August) was in 1976 with a mean of 17.77°C, breaking the previous record of 17.60°C set in 1826.
- The warmest autumn (September, October, November) was in 2006 with a mean of 12.62°C, breaking the previous record of 11.80°C set in 1730.
- The mildest winter (December, January, February) was in 1869 with a mean of 6.77°C, breaking the previous record of 6.53°C set in 1834.
- The mildest January was in 1916 with a mean of 7.5°C, breaking the previous record of 7.3°C set in 1796
- The mildest February was in 1779 with a mean of 7.9°C, breaking the previous record of 6.8°C set in 1739
- The warmest March was in 1957 with a mean of 9.2°C, breaking the previous record of 9.1°C set in 1938
- The warmest April was in 2007 with a mean of 11.2°C, breaking the previous record of 10.6°C set in 1865
- The warmest May was in 1833 with a mean of 15.1°C, breaking the previous record of 13.8°C set in 1758
- The hottest June was in 1846 with a mean of 18.2°C, breaking the previous record of 18.0°C set in 1676
- The hottest July was in 2006 with a mean of 19.7°C, breaking the previous record of 19.5°C set in 1983. July 2006 was also the hottest month in the series
- The hottest August was in 1995 with a mean of 19.2°C, breaking the previous record of 18.7°C set in 1975
- The warmest September was in 2006 with a mean of 16.8°C, breaking the record of 16.6°C set in 1729.
- The warmest October was in 2001 with a mean of 13.3°C, breaking the previous record of 13.0°C set in 1969
- The warmest November was in 1994 with a mean of 10.1°C, breaking the previous record of 9.5°C set in 1818
- The mildest December was in 1974 and 1934 with a mean of 8.1°C, breaking the previous record of 7.7°C set in 1852
- The coldest year was 1740 at a mean 6.84 °C, coincidentally almost exactly 4° behind the record hottest.
- The coldest ever month was January 1795 with a mean temperature of -3.1°C.
- Despite the fact that 6 new hottest recorded months have been set in the last 15 years, 60 years have passed since the last time a coldest month record was broken, the coldest February in 1947 (mean temperature -1.9°C), breaking a record set in 1895.
- The coldest winter (December, January, February) was in 1684 with a mean of -1.17°C. The devastating winter centred on January 1963 was the 3rd coldest (mean -0.33°C).
- The coldest summer was in 1725 with a mean of 13.10°C.
- Four months still have records that were set in the 17th century (March, May, June and September).
- G. Manley, "Central England temperatures: monthly means 1659 to 1973.", Quarterly J. of the Royal Meteorological Society, vol. 100, pp. 389-405 (1974).
- D.E. Parker, T.P. Legg and C. Folland, "A new daily Central England Temperature series 1772-1991," Int. J. Climatol., vol. 12, pp.317-342 (1992).
- Met Office Historical Central England Temperature Data Data access for academics only.
- Met Office Hadley Centre CET pages