western districts of England and Wales; it W;LS around the average in some bordcr areas but was below the average over most of Scotland with deficits of as much as jo hours in some western districts.

October, Movernber and DeceinOer October was a dry montli in western Scotland, but in soutli-east England

rainfall was more than twice the average and as much as $30 per ccnt of the average arouncl the Manston arca. Following two stormy clays on the 18th and 19th with widespread gales and frequent heavy thunderstorms, renewed heavy rain on tlie 2znd led to widespread floods in Midland and Southern districts. Hurn recorded more than z in. of rain on the zznd, about half of which fell in an hour. Mean temperatures were mainly below the average except in soutli-east England where day temperatures were mainly above the average during the first three wccks; nights were unusually warm on the 3rd- 7th and 13th-rgth. It was a dull month except in western districts; Northern Ireland was gtxierally sunny and parts of soutli-west England and western Scotland had more than 120 per cent of their average.

November was cold with winds from a northerly quarter throughout the month except for three or four days during the first week and three days towards the end of the second week. Temperatures were mainly below the average although there were milder spells; one of these on the 7th-8th was mainly confined to south-cast England but others on the rrth-15th and 26th- 28th were more general. Kainfall was generally below the average except in the eastern half of the country and parts of the Midlands; it ranged from 50 per cent of the average locally in Oxfordshire to 150 per cent of the average in the extreme east of Kent. Sunshine was slightly below the average in England and U’ales but a little above in Scotland; it was greater in the west than in the cast.

December was rather a wet month-Manchester had nearly 5 in. of rainfall during the month, nearly half as much again as its December average. Tem- perature rangcd from a mean of 2 .4 deg C above the normal in the Cardiff area to slightly below normal in Scotland and Northern Ireland. Sunshine was below average in the extreme south of England but was more than twice the average in parts of the north-east.

APRIL WARMTH : A PREDICTOR FOR THE COMING SUMMER? By I. T. LYALI.

Hay (1966) t>stalilished a relationship between summer rainfall in England a i d Wales and April temperatures over Europe and Canada. The author had previously noted that the three warin, dry summers of 1949, 1955 and 1959 had all been prcxcecdcd by warm Aprils in this countyy.

An attcmpt has therefore been made to correlate April warmth (or cold- ness) with the following summer using the summer index, I s k , devised by Poulter (1962) and tempcraturc records kept at Newark (Notts.) for the period 1949-66. The value of I s k was that for Kew as local sunshine statistics for

I62

Newark were not available, and it seems a reasonable assumption that the year-to-year variation in I s k will be of the same order over most of lowland, south-eastem Britain.

The data are summarized in Table I. A first glance at the table shows that those years with an April mean temperature a t or below the median value of g.o”C were followed with summers whose I s k values ranged between 619-707, with an average value of 665. In those years when the April mean temperature was above median, the value of I s i , ranged from 683 to 759 with an average value of 713.

The analysis may be carried a stage further. The average I s k for 1949-66 is 685. Approximately half the years come within &20 of the mean value; on this basis we may designate summers above 705 as ‘good’, 686-705 as ‘above average’, 666485 as ‘below average’ and below 666 as ‘poor’.

On a similar basis, we may classify Aprils into four groups: a mean tem- perature of IO-OOC and above is ‘warm’, 9.0 to g*g°C is ‘above average’, 8.0 to 8-g”C is ‘below average’ and below 8.o”C is ‘cold’. TABLE I. Mean April temperatures at Newark and the Poulter index of the ensuing

summer (1949-66)

* April temperature (“c) I s k April temperature (“C) IS&

1963 7957 1960 1964 I952 I955 1959 1961 I949

9 . 0 9 .1 9’5 9 . 6

10.3 10.7

10’0 10’2

1 1 ’ 0

670 695 683 689 709 721 759 700 746

* This mean temperature is the arithmetic mean of the average daily maximum and

On the above classifications, we find: Five ‘warm’ Aprils, followed by four ‘good’ summers and one ‘above

average’ (average I s k = 727). Four ‘above average’ Aprils, followed by two ‘above average’ summers and

two ‘below average’ (average I s k = 688). Five ‘below average’ Aprils, followed by one ‘good’, one ‘below average’ and

three ‘poor’ summers (average I s k = 666). Four ‘cold‘ Aprils followed by one ‘above average’, two ‘below average’ and

one ‘poor’ summer (average I s k = 666). This would thus seem to give a rule of some predictive value, especially

when April is ‘warm’. None of the five ‘warm’ Aprils between 1949 and 1966 were followed by a ‘below-average’ summer; the lowest I s k being 700 in 1961 whilst the average value of 727 is 41 above the overall average and represents a summer comparable to 1955.

Poulter (1966) published a table showing three interlocking 11-year cycles of good summers, and predicted a good summer for 1966. April 1966 was dismally cold and the summer I s k was 669. Maybe, as occasionally appears to happen, the good summer will appear one year out-of-step, in 1967.

HAY, R. F. M. 1966 Spring temperature anomalies and summer rainfall.

POULTER, R. M. 1962 The next few summers in London. Ibid., 17 (a), pp. 253-5 1966 Poulter’s index of summer weather in London. Ibid..

the average nightly minimum.

REFERENCES

Weather, 21 (6), pp. 21g-227

21 (31, P. 109

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