90 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



THE FIFTEENTH REPORT ON METEOROLOGICAL 

 OBSERVATIONS AT WISLEY. 



By the late R. H. Curtis, Hon. F.R.H.S. 



The most outstanding feature of the weather of 1918 was undoubtedly 

 its unusual wetness over the greater part of the kingdom, although 

 the excess of rain above the normal varied considerably in different 

 districts. At Wisley the total yearly fall exceeded the average by 

 twenty-three per cent. ; but in July the amount of rain which was 

 measured at the Gardens was double, and in September treble, the usual 

 fall for those months ; whilst in August it totalled but little more than 

 three-quarters of an inch, or only one-third of the average amount. 

 The only other months with a fall of rain of less than an inch were 

 February and March, both of which were unusually dry. 



This illustrates very well the need for a reasonably long series 

 of observations upon which to base average values if they are to 

 represent climate fairly ; and in this connexion we may note that, 

 with the completion of this year's results, we shall be able to improve 

 our basis for such comparisons at Wisley, by including in future 

 mean values the observations of a third pentad, the closing year of 

 which is that now under review. 



As regards temperature the mean for the whole year was nearly 

 normal ; but in some parts of the country, in individual months, 

 the deviations from normal were considerable, both above and below. 

 The coldest night of the year occurred in January, when the 

 thermometer registered 4 0 Fahr. on the grass. February was unusually 

 mild throughout. March was warm, but April decidedly cool, with 

 some sharp frosts which did considerable harm to fruit trees. May 

 was the warmest May experienced for several years ; but with the 

 warmth came a plague of insects which did great damage to foliage 

 of all kinds. A feature of June was the abnormal frequency of 

 night-frosts, but there were also a few exceptionally hot days, and 

 these to some extent balanced each other, so that the average 

 temperature was nearly normal. July was cool and unseasonable, 

 and during the middle of the month very wet also. In August the 

 temperature varied a good deal, but on the whole the weather was 

 fairly normal ; the hottest day of the month was the 22nd, but the 

 following day was almost the coldest, and really hot days were rare. 

 September was really cold all through, occasionally there were night 

 frosts, and in the screen, four feet above the ground, the thermometer 

 at Wisley only once reached 70 0 , but on another occasion it fell very 

 nearly to the freezing point. October was a normal month as regards 

 temperature, but it was followed by a cool November, whilst the 



