How’s the Weather at Reunions? PAW Looked at 10 Years of Data

Reunions are remembered for connecting with classmates, dancing the night away, the P-rade, and, of course, the weather in any given year. Since Reunions is a primarily outdoor event, attendees have been subjected to scorching temperatures and torrential downpours in recent years.

How warm or cold, on average, is Reunions? How often does rain force attendees to take shelter under tents — or indoors? And how often does extreme weather affect the P-rade, the highlight of the weekend?

To answer these questions, PAW gathered data on the weather for each of the four days of Reunions across the last 10 occasions of this event — each Reunions since 2013, as it was canceled in 2020 and 2021 due to COVID-19. Weather data for the Princeton region is recorded at the National Oceanic and Atmospheric Administration’s weather station at Trenton-Mercer Airport.

Temperature ticker

Across the dataset, the average high temperature at Reunions is 81 degrees, while the average low is 60 degrees. These numbers track closely to the mean daily maximum and minimum for June recorded at Trenton-Mercer Airport, which are 81 and 61 degrees, respectively.

Average Temperatures

When looking at how these figures have changed over time, the average high temperature has ranged from 72 to 89 degrees and the average low from 48 to 70. Among the past 10 Reunions, 2013 stands out as the warmest, with an average high temperature across the weekend of 89 and an average low of 70. The coldest was 2023, with temperatures failing to break 77 degrees at any point over the weekend and nighttime lows dropping into the high 40s.

Temperature by Day

It’s often said that the P-rade seems to be held on the hottest day of Reunions. This wisdom is partially supported by the data, with Saturday narrowly edging out Friday and Sunday to have the highest average high temperature at 83 degrees. Saturday has been the hottest day of Reunions for five out of the last 10 gatherings.

Across the past 10 Reunions, Thursday has tended to be the coolest day, with an average high temperature of 78 degrees. Across all days, the average low temperature has been 60 degrees.

Temperature is not the sole factor in ensuring a comfortable day outdoors — humidity also plays a large role. The National Weather Service recommends looking at the dew point to determine whether a day is dry or humid. The service defines a dew point below 55 degrees as “dry and comfortable,” between 55 and 65 degrees as “becoming sticky,” and greater than 65 degrees as “becoming oppressive.”

Dew Point by Year

Using this scale, only three of the past 10 Reunions could be characterized as “dry and comfortable” by looking at the average dew point across the four days of the event — 2014, 2017, and 2023. The average dew point generally sits in the 
60-to- 65-degree range. Reunions 2013 stands out as the most humid, with an average dew point of 65 degrees.

Despite Reunions occurring mostly under the white tents that dot campus, it remains a true outdoor activity, making rain a huge threat. Of the 40 individual days of Reunions across the last 10 Reunions held, 27 were completely dry, while 13 saw at least 0.01 inches of rain.

Only once has more than one inch of rain fallen on Reunions in a single day since 2013 — and at the worst possible time. On Saturday, June 2, 2018, a large thunderstorm moved over the Princeton area just before 3 p.m. — shortly after the P-rade had commenced down Elm Drive. At about 2:45 pm., parade marshals noted to the crowd that lightning strikes had been spotted near campus, canceling the parade and advising participants to seek shelter. Some attempted to defy the order, PAW reported at the time, continuing to march down Elm, but most were driven inside when a downpour began at about 3:15 p.m.

The P-rade in 2018 was the first time the event had been canceled since 1953, when rain also made the march down Elm impossible.

Blown Away

The 2018 P-rade fell on the fifth-windiest day of Reunions across the last 10 times Reunions was held. The maximum wind speed was 18 mph that day, with gusts reaching up to 30 mph. The windiest day of Reunions since 2013 was Friday, May 20, 2022, when the maximum wind speed reached 22 mph and gusts were clocked as high as 35 mph.

Across the past 10 Reunions, the Princeton community has, by and large, been blessed with warm weather and clear skies for its annual gathering. But, as 2018’s P-rade shows, rain has threatened the event before in a dramatic fashion. As Princeton graduates find themselves going back to Old Nassau for this year’s Reunions, expect warm weather — but don’t be surprised if it rains on your parade.