October: Record warmth; late month sou’easter

NASHUA – Unseasonable warmth was the rule through most of October, helping to boost the month to the warmest on record since temperature records began in 1885 in Nashua. Rainfall was sparse through the first three weeks of the month, then the floodgates opened during the final week, including a damaging windstorm just before Halloween.

October seemed a little more like September with respect to temperature, as early fall warmth lingered for much of the month. Temperatures averaged more than 10 degrees above normal on 14 days, with a peak of 22 degrees above normal on the 24th. Only five days saw readings average cooler than normal during October.

October set a new monthly record for warmth at Nashua with a monthly average of 57.8 degrees. This value broke the previous record of 56.2 degrees from 1947 by 1.6 degrees, impressive in itself.

October 1947 was the driest October on record for the Gate City, and is famous for the widespread wildfires across Maine. Fires burned across much of Acadia National Park and numerous mansions were reduced to cinders. Nashua also saw a 91-degree reading during October 1947.

The reasons behind the warmth can be tied to the pattern that we saw during the second half of September. A strong upper level ridge across the eastern and southeastern U.S. guided warmth our way and kept the main jet stream across southern Canada. A trough across the western U.S. brought cold and record snow to parts of the northern Rockies.

Temperatures during October were not too much cooler than we would normally observe during a typical September. The average temperature during October was but 3.5 degrees cooler than September’s normal.

Despite the persistent warmth, no record high readings were set, but there were three days with record high-low temperatures. A record high-low temperature occurs when the low temperature for a given day is higher than at any other time on that date.

The list of record high-low temperatures includes 63 on the 19th, bettering 62 from 1913, 63 on the 25th breaking 56 from 2001, and 58 on the 26th besting 53 from 1908.

The seasons’ first 32-degree reading was recorded on Oct. 17, four days later than the normal. The first hard freeze has yet to occur, but most vegetation has died for this season.

Sunshine helped with the warmth with a sunnier-than-average month recorded at Blue Hill Observatory in Milton, Massachusetts. Blue Hill is the nearest location to Nashua that records sunshine data.

For October, Blue Hill saw 58 percent of the possible sunshine, 3 percent above normal. Data kept in Hudson reveals that we saw 15 sunny days, 7 partly cloudy days and nine cloudy days during October.

Rainfall during October was well above normal, but most of the total came during the final week of the month. During the first three weeks of October, the combination of falling leaves and lack of rainfall raised the fire danger.

That changed beginning on the 24th, when a moisture-filled weather system dropped more than 2 inches of rain on the area. We would not be finished with this event as a second storm developed across eastern New England from the 26th into the 27th, depositing another 1.5 inches.

Before this complex storm system would exit the area, we already had eyes on a new storm with greater potential. Moisture from what was once Tropical Storm Philippe near Florida was forecast to be pulled into a rapidly developing gale along the Mid-Atlantic coast on Oct. 29.

Model forecasts were indicating explosive development with lots of wind and heavy amounts of rain. As we all know this is what happened during the early morning hours of Oct. 30.

This storm traveled from the Mid-Atlantic Coast northward through eastern New York state, producing what we in the weather industry call a southeaster. Many are familiar with the term nor’easter, and these are the same kind of storm just a different track.

Nor’easters typically track from the Virginia Capes to near or east of Cape Cod, bringing us northeast to northerly winds and chilly rain or snow. Sou’easters tend to move from the coastal Mid-Atlantic States northward through eastern New York state bringing us mild temperatures, strong east to southeast winds and rain.

Sou’easters were a pretty common visitor to New England during the 70s and 80s, sometimes with the same results of our late-October storm, wind damage and power outages. During the past quarter century, nor’easters have been more dominant, bringing us the upswing in snow amounts we’ve endured since the 1992-93 season.

Could we see a change back to weather patterns of a few decades ago? Only time will tell, but we certainly know weather and climate go through different regimes of varying lengths. Weather and climate are constantly changing, both in the short term and long term. Climate change is a very normal and natural occurrence.

Given that the past 25 years have seen greater snow amounts than during the 15 years prior, it would seem natural that we might enter a period of less snowfall soon. That plays into the outlook for the winter. Early signs would imply a slow start to winter and a fast finish, similar to several winters of the past 10 years.

Clues as to how the winter will go are still to be revealed during November. Many times when both October and November are mild, we see a mild winter. On the other hand, a mild winter doesn’t necessarily mean little snow either. Last winter was mild with above-normal snowfall.

A normal November in the Gate City brings us increasing cold, more storminess and more threats for some snow, especially later in the month, but normal is unusual in itself. During some Novembers, winter-like weather can start even before the official start of meteorological winter on Dec. 1.

November 1950 saw temperatures reach the low 80s, while subzero cold was recorded on the day after Thanksgiving in 1989. Snowfall averages just a couple of inches, but some years have brought no snow, while others have produced a foot or more. Indian summer is an infrequent visitor during November. We should all keep in mind that being abnormal is what is normal for weather and climate.

Weather & Climate is written by Doug Webster, a Hudson resident and senior meteorologist at Hometown Forecast Services in Nashua.