WATERLOO REGION — Waterloo Region had its hottest May and coldest April in more than 100 years.

Records dating back to 1915 show that the region had its chilliest April ever with temperatures 4 C below average; May went the other way with temperatures nearly 4.5 C above average. "(It's) what some people call weather whiplash," Frank Seglenieks, co-ordinator at the University of Waterloo Weather Station, said of the back-to-back weather extremes.

April's warmest day hit a high of 18.5 C and its coldest, a low of - 8 C. The month's average daily high temperature was only 6.8 C; its average low was -2.8 C.

"Spring never really seemed to get started there in April and you could tell with peoples plants and gardens," said Seglenieks. "And then it literally was like the calendar turned into May and then, hey, the world kind of woke up."

The mercury hit a high of 31.3 C in May and dropped as low as 1.9 C, but never dipped below zero. The average daily high temperature was 23.5 C and the average low was 10.3 C.

The last week of the month saw a surge of warm air from the Gulf of Mexico, which gave the region warm, humid weather, said Gerald Cheng, a meteorologist with Environment Canada

But for those who grew accustomed to the sunshine and heat, the temperatures in the first few days of June certainly came as a surprise, with highs below 20 C. "We're seeing the jet stream dipping south," said Cheng.

While warm weather will move into Ontario later in the work week, with seasonal temperatures in the low 20s, by Saturday we can expect another dip. And, possibly some rain, said Cheng.