May brought another unusually rainy month on top of the wettest April on record.
All that precipitation helped to further boost water levels to all-time highs on Lake Ontario and 20-year highs on Lake Erie.
It was also the first cooler-than-average May since 2008.
Following April's form with a few deluges of rain accounting for most of the month's precipitation, more than 70 percent of the 6.35 inches that fell in May came on three record-setting days – May 1, 1.29 inches; May 5, 1.37 inches; and May 25, 1.79 inches.
It was the seventh wettest May on record in Buffalo dating back to 1870.
There were 14 days with measurable precipitation in May, which is about one more than average. Last year, there were only seven such days.
There were three days in May with at least 1 inch of rain. Only May 2011's four days is higher.
May added more water to the unusually wet spring. Meteorological spring includes March, April and May.
The 17.09 inches of precipitation logged at the Buffalo Niagara International Airport this year made 2017 the second-wettest spring in the city's weather recorded history.
Dating back to 1870, only 2011's 18.41 inches was higher.
There was no snowfall recorded in May.
By the numbers:
Total May rainfall: 6.35 inches, (2.89 inches above normal).
May 2016: 1.21 inches. May 2015: 3.5 inches.
Total May snowfall: 0 inches, (0.3 inches below normal).
May 2016: trace. May 2015: 0 inches.
Daily high: 1.79 inches, May 25.
Historical records: Precipitation, 8.09 inches, May 2011. Snowfall, 7.9 inches, May 1989.
- May 1: 1.29 inches of rainfall broke the former daily record of 0.77 inches, set in 1875.
- May 5: 1.37 inches of rainfall broke the former daily record of 0.98 inches, set in 1914.
- May 25: 1.79 inches of rainfall broke the former daily record of 1.21 inches, set in 1874.
For the second time in three months, and only the third time in 22 months, the monthly temperature in Buffalo – 56.1 degrees – ran below normal.
That was because the daytime highs were more than two degrees cooler than average. Overnight lows were actually warmer than average.
Highs and lows
HIGH: 83 degrees, May 18.
LOW: 34 degrees, May 8, May 9.
Monthly averages for May
HIGH: 63.9 degrees (2.6 degrees below normal). Last year: 68.8 degrees.
LOW: 48.3 degrees (0.9 degrees above normal). Last year: 49.0 degrees.
MEAN: 56.1 degrees, (0.8 degrees below normal). Last year: 58.9 degrees.
40s: 3 days // 50s: 6 days // 60s: 12 days // 70s: 8 days // 80s: 2 days
- The low temperature of 64 degrees on May 17 tied the warmest minimum temperature for the date set in 1889.
The peak wind gust for the month was 51 mph. It was a southwest wind recorded on May 1.
May 18 was both the warmest and the breeziest day of the month, with an average wind speed of 17.4 mph and maximum sustained wind of 32 mph.
Rising lake waters made all the headlines on the lakes during May.
Lake Ontario's water level reached unprecedentedly high marks in May, flooding coastal areas in Niagara and Orleans counties.
Lake Erie's average water level crept up close to historically high marks as the lake waters swelled to numbers not seen in nearly two decades.
Lake Ontario's average monthly water level for May was more than 2½ feet above its long-term average, and where it was just a year ago, according to U.S. Army Corps of Engineers' statistics.
Water levels were measured on Lake Ontario at an average of 248.68 feet above sea level. The previous high water mark for May was 248.46 inches, set in 1973.
The highest-ever recorded average water level was 248.56 feet above sea level set in June 1952.
On Lake Erie, heavy precipitation in the Great Lakes region also swelled waters in its basin.
The water level – 573.56 feet above sea level – was more than 1½ feet above its long-term average and the highest it has been since May 1998.
It was about 6 inches less than its all-time highest water level, 574.05 feet, set in 1986.
Lake Erie temperature
Lake Erie's water temperature at Buffalo warmed up 12 degrees in May.
May 1: 47 degrees / May 31: 58 degrees
Highest temperature: 58 degrees, May 31. (Historical High: 66 degrees, May 30 and 31, 1991.)
Lowest temperature: 46, May 2. (Historical Low: 32 degrees, various dates. Most recently on May 1, 2014.)
Average temperature: 51.7 degrees.
There was no ice on either Lake Erie or Lake Ontario during May.
Three other interesting facts from May 2017:
- Nearly identical amounts of rain fell in April and May, 6.38 inches and 6.35 inches respectively.
- Lake Ontario's water level grew by more than a foot from May 1 to May 31. It started the month at 247.80 feet above sea level and ended the month at 248.91 feet above sea level.
- The two 80-degree days in May (May 17 and 18) are the fewest number of 80-degree days in Buffalo in May since there were zero in 2009.
Sources: National Weather Service, Great Lakes Environmental Research Laboratory, U.S. Army Corps of Engineers
Past 2017 weather roundups: