At approximately 4:25 p.m. EDT, the tornado developed in a forest near the town of Petersham, and proceeded to move through Barre, where two people were killed.

In combination with the warm unstable air in place over the Great Plains, and an elevated mixed layer from the desert southwest, this led to conditions favorable for severe thunderstorms and tornadoes.

[10] On the morning of June 9, the low pressure system had moved northeastward into Ontario near the south end of Hudson Bay.

In the mid-atmosphere, the elevated mixed layer was still in place, keeping storms from forming earlier in the day before maximum temperatures were reached.

[7] By afternoon, temperatures in Worcester had reached 80 °F (27 °C), with a dew point of 66 °F (19 °C); in combination with cold air aloft, this meant that atmospheric conditions were very unstable and conducive to severe weather.

Along with this, amplified wind shear was present into the afternoon of June 9, which made conditions in the atmosphere supportive of supercell development, and the formation of tornadoes.

[citation needed] After brushing Petersham (occasionally with twin funnels several hundred feet apart), the tornado tracked southeastwards and slammed into the rural towns of Barre and Rutland, with two fatalities occurring at each of these locations.

[13] The now massive tornado then tore directly through suburban Holden, completely wiping out the Brentwood Estates subdivision, resulting in fatalities.

A 12-ton (10.89 metric-ton) bus was picked up, rolled over several times, and thrown against the newly constructed Curtis Apartments in Great Brook Valley, resulting in the deaths of two passengers.

Across Boylston St. from the Curtis Apartments, the Brookside Home Farm (a city-operated dairy facility and laundry) sustained total damage, with six men killed and the loss of its herd of 80 Holsteins.

A separate F3 tornado also struck about the same time the warning was issued, in the nearby communities of Sutton, Northbridge, Mendon, Bellingham, Franklin, Wrentham and Mansfield in Massachusetts, injuring 17 persons.

Airborne debris was strewn eastward, reaching the Blue Hill Meteorological Observatory 35 miles (56 km) away, and even out over Massachusetts Bay and the Atlantic Ocean.

[13] The Worcester tornado's greatest effect on the nation was its being the principal catalyst for the Storm Prediction Center's reorganization on June 17, 1953, and subsequent implementation of a nationwide radar/storm spotter system.