Summer 2015: Wet to normal to hot

In a season with long stretches of pleasant, unremarkable weather, it's been easy for Rochesterians to overlook this fact: In several ways this has been a somewhat remarkable summer.

Owing in large part to a soaking start and an on-going series of gully washers, this has been one of the rainiest summers on record. Owing to the belated arrival of July-like heat, these closing weeks of summer have been among the hottest ever experienced here.

“September has just really been crushing it as far as temperatures,’ said Samantha Borisoff, a climatologist at the Northeast Regional Climate Center in Ithaca. “For the first half of the month, Rochester was almost seven degrees above normal. It’s the eighth warmest first half of September on record.”

The late-season heat wave stands in contrast to the bulk of the summer, which gave Rochester moderate temperatures and half the normal number of truly hot days.

Rain does that one better. This was the fifth rainiest summer on record here, Borisoff said. Rochester measured near 14 ½ inches of precipitation, about 40 percent more than normal.

But the way that rain fell may have obscured that fact.

While June was quite damp, Rochester actually experienced fewer days of measurable rain that it usually does in the summertime. Weeks went by in August and early September with hardly any rain at all, withering lawns and turning the leaves on corn stalks brown.

Forecast: This weekend's weather report

But scattered through the summer were big downpours that pushed the seasonal rainfall total sky-high. Our five biggest downpours alone provided almost enough rain to equal the area’s normal summer total.

Everything else was watery gravy.

“That’s kind of been the pattern across the Northeast, where we’ve had these lulls in precipitation and then a heavy downburst, and then another lull, and then another heavy downburst,” Borisoff said.

One side effect of the summer’s conditions was a bumper crop of blue-green algae in New York lakes, ponds and rivers.

As of Friday, the state Department of Environmental Conservation had placed 139 water bodies on its blue-green algal bloom alert webpage. That’s far more than any of the three previous years the alert page has been in existence, though part of the increase likely is due to stepped-up monitoring and reporting. For the first time, four Finger Lakes appear on the list simultaneously.

Blue-green algae still plague Canandaigua Lake

“I think a lot of the  blooms we have been seeing are a direct result from the relatively heavy rains in early summer followed by the stink-hot weather in late summer. It sets up perfect conditions for a algal bloom,” said Gregory Boyer, a biochemistry professor at the State University College of Environmental Science and Forestry in Syracuse and perhaps the state’s leading expert on blue-green algae.

The early-summer rainfall did cause problems for local growers, fostering fungal or bacterial diseases and slowing planting in some cases. Two of the region's signature crops, grapes and apples, both incurred some extra risk of disease due to the rain, said specialists for Cornell Cooperative Extension.

But apple growers should be able to combat problems with judicious management, said Deborah Breth, an Orleans County area extension specialist in fruit who works the fruit-belt counties along the Lake Ontario shoreline. There's a compensating weather bonus, she noted:  The late-season warm, sunny weather built up the fruit sugars.

"The quality's going to be good," Breth said.

Likewise, June's heavy rains interfered with grape formation and gave fungal diseases an extra foothold, said Hans Walter-Peterson, viticulture specialist for Cornell Cooperative Extension of Yates County. But vineyards are like orchards: September is trumping June.

"Fortunately this dry September has kind of helped control a lot of that. We’re seeing some of this disease develop but we’re not seeing as much as we potentially could have because of this dry weather," he said. As well, the warm, dry weather has advanced the harvest, which began about a week early this year.

"So far, so good," Walter-Peterson said. "Just keep hoping for more of the same."

SORR@DemocratandChronicle.com