The January 5 1950 edition of the Toronto Daily Star reported on unusually mild weather that winter, blaming it on Russian atomic testing.
I looked up the weather records for December 1949 and for the winter of 1950 to see whether the temperatures had been unusually mild. I discovered that December 1949 had been warmer than usual: there were five days with a high temperature above 10C, and only one stretch that was unusually cold (December 6 to 10).
The first part of January continued the trend: January 3 had a high of 13.9C, and it was 11.1C on the 4th. There were additional mild days: it was 13.3C on the 13th, 11.7C on the 26th, and a startlingly warm 16.7C on the 25th. After that, things settled down a bit: there were no days in February above 3.3C, and the high temperature on February 20 was -16.1C. So the Soviets’ influence on the weather must have worn out by then.