A quick flip of the switch from cold to warm led to the warmest May on record.
Daily temperatures averaged about five degrees above normal and two new highs were set.
“The cool and wet pattern which prevailed during the past three months made a sudden shift during May,” forecaster Ron Lakeman, from the Castlegar weather office, reported in his month-end summary.
An upper ridge of high pressure built over southern B.C. for dry and unseasonably warm conditions during the first week of the month and prevailed again from May 12 to May 18.
“It was the warmest May on record,” Lakeman noted. “The average daily maximum temperature was 4.8 degrees warmer than normal. The mean monthly temperature was 16.9 degrees which is almost 1 degree warmer than the previous warmest May of 1993.”
Mid-month sunshine set two new record highs. The first was on May 14 when the temperature neared 31 C and the second was the following day when the mercury climbed to 32 C.
Aside from the warm days, Lakeman noted the few days of rain. Measurable rain fell on only eight days, which he reported as half the usual 16 days of rain expected in May.
The most significant rainfall of 20 millimetres (mm) fell over 48 hours beginning May 9, as a large Pacific system slowly pushed southeastward across the region.
A localized thundershower produced a rapid 13.4 mm of rain during the afternoon of May 24, and an upper trough of low pressure prevailed for cooler and unsettled conditions during the final few days of the month.
The total monthly rainfall was 72 per cent of normal.
Although May was the warmest on record, the record daily high remains 34.5 C from May 2006. According to Lakeman’s statistics, the coldest day for the fifth month still stands at -4.7 C from May 1, 2013.
