NATURAL HISTORY, TORONTO REGION
during April, are now practically over, and with leaps and bounds vegetation goes forward. By the 15th day most of the spring wild flowers are in bloom and many trees are in full leaf. About ten days later horse chestnut, lilac and apple are in bloom, and incubation by migratory birds is well on the way. The average date of the last spring frost is May 4th. The warmest May on record was that of 1911, with a mean temperature of 61°.2, and the coldest that of 1867, with a mean of 46°.5. It is not uncommon in this month for the daily maxima temperatures to exceed 70° for spells of a week or ten days.
One of the outstanding features of the Toronto summer is the fact that wholly overcast and rainy days are of rare occurrence, the rainfall occurring in showers and thunderstorms, while days of bright sunshine are numerous ; in fact, from the middle of June until the end of August one may almost count on days of at least part sunshine. There is an aver-age of 791 hours of sunshine in the three months.
By May 20th the normal daily temperature has risen to 53°.5, with an average daily maximum of 64° and occasional days of 80°. June has an average daily maximum of 72°, July 78°, and August 76°, and during the first ten days of September it is still above 70°. Spells of great heat occasionally occur, but temperatures of 90° are not of frequent occurrence. Up to 1911 the highest temperature ever recorded was 98°.6, but a period of heat during the first few days of July, 1911, broke all records, and