The 2011 Halloween nor'easter, sometimes referred to as "Snowtober,"[4] "Shocktober,"[5] "Storm Alfred,"[6] and "Oktoberblast," was a large low pressure area that produced unusually early snowfall across the northeastern United States and the Canadian Maritimes.

As it moved up the East Coast, its associated snowfall broke records in at least 20 cities for total accumulations, resulting in a rare "white Halloween" two days later.

[10] Early on October 28, 2011, a ridge over Canada advected an unseasonably cold air mass across the Mid-Atlantic states and New England; at the same time, a surface low-pressure area began developing along the coast of Louisiana.

At the same time, an area of precipitation extended from South Carolina through Pennsylvania, mostly falling as rain with some snow observed at higher elevations.

[14] As the system moved to the northeast through the day, it produced widespread snow and winds near hurricane-strength north of the cyclone's warm front over the open waters of the Atlantic Ocean.

[17] Overnight into October 30, the storm passed south of Nantucket, and it moved over Nova Scotia later that day with a barometric pressure of 975 mb (28.8 inHg).

[1] As the system moved out into the Atlantic Ocean, it reached a minimum barometric pressure of 971 mb (28.7 inHg) as it passed to the east of the island of Newfoundland late on October 31.

[23] Connecticut governor Dan Malloy opened the state's Emergency Operations Center in Hartford, which included members of the transportation, health, and energy departments.

[25] Occupy Wall Street protesters pledged to remain in Lower Manhattan's Zucotti Park despite the weather, obtaining coats and blankets.

[1] At least 20 cities reported record-breaking totals,[25] and the peak of 19 in (48 cm) in West Milford, New Jersey broke that state's record for highest snowfall in October.

[31] An automated marine weather station at Mount Desert Rock off the coast of Maine recorded a top gust of 77.2 mph (124.2 km/h).

[38] Across the Northeast, the combination of high winds and wet, heavy snow downed trees, most of which retained their leaves, did extensive damage.

[39] In New York City, a thousand trees were estimated to have fallen in Central Park, far more than had been damaged by Hurricane Irene two months earlier,[40] just as had been reported in Connecticut.

In communities without electricity, where tree limbs and wires were down, trick-or-treating was delayed until days when it was expected to be back and repairs had made the streets safer.

On the other hand, another popular Halloween destination, Salem, Massachusetts, location of the 1692 witch trials, was unaffected due to its minimal snowfall.

Residents of Glen Rock, New Jersey, organized a "trunk-or-treat" party at the local high school's football field, where children went around to parked sport-utility vehicles.

"[41] At UMass Amherst, the storm caused a power outage over a traditional party weekend at the college that lasted throughout most of the night on Saturday, October 29.

She noted the town had managed to celebrate the holiday that day on its village green despite considerable storm damage and continued power outages.

In Connecticut, Weston High School, which had power, opened its library for students wishing to study or work on their applications; movies were shown in the auditorium.

As powerless houses grew cold, residents bundled up and kept under blankets, went to stay or visit with others who had electricity, or used their car heaters to temporarily warm-up.

[62] Some, frustrated by long blackouts after other recent storms, considered leaving the region or moving to cities where power lines were underground.

[63] About half a million households in New Jersey lost electricity, prompting a state of emergency declaration from governor Chris Christie.

[64] In Connecticut, Governor Dannel Malloy declared a state of emergency late on October 29,[48] after 830,000 people lost power, breaking the record set after Hurricane Irene.

Customers still suffering outages continued to cope as best they could, by sleeping at the homes of friends who had already had their electricity restored, taking showers at work and storing perishable foods outside.

Malloy said they had "missed their own target" and ordered an investigation into their preparation and restoration efforts to be led by James Lee Witt, director of the Federal Emergency Management Agency during the Clinton Administration.

As a result, it was harder to mobilize them when the effects turned out to be far worse than they anticipated despite warnings from the NWS using terms such as "historic" and "catastrophic" prior to the storm.