Rose Parade 2024: Ready your umbrellas, there’s a chance of rain

On New Year’s Day the unthinkable may happen along the Pasadena Rose Parade 5.5-mile historic route — a spot of rain (cue gasp).

Such an outcome is very rare. In fact, over the course of its 134-year history, the event has had 124 sunny iterations and just 10 soggy ones.

While attendees are praying that the parade’s dry weather streak will hold, they should have their ponchos and umbrellas at the ready should this year prove an exception.

As of Wednesday, the National Weather Forecast predicted a chance of showers on New Year’s morning, but added that this forecast is far from certain.

“There is a chance of light rain in Pasadena on New Years Day,” the report states, noting that their models are “having a very difficult time with the details of the weather pattern” and “unfortunately confidence in the forecast is still rather low.”

In any scenario, the potential drizzle is not expected to be anywhere near as heavy as the winter storm that drenched L.A. County last week.

The last time parade-goers were rained on was in 2006 when a huge downpour prompted parade organizers to consider calling off the event and the National Weather Service to issue a flash flood warning.

Despite the high wind and torrential rain, spirits along the parade route were high and parade organizers were impressed by the resolve of those who remained in attendance.

“I must tell you I was in shock to see how many people obviously wanted to come,” said Bill Flinn, chief operating officer for the Pasadena Tournament of Roses Association in 2006. “Considering the weather, it was a near-perfect parade.”

Only four of the parade’s 48 floats experienced mechanical issues and needed to be towed, he added.

For most people the great storm of ’06 was the last rainy parade they can remember. Prior to that it hadn’t rained on the Rose Parade since 1955.

So why exactly is it so rare for Pasadena to see rain on New Years day?

The answer is part odds, part science, explained Daniel Swain, climate scientist at UCLA’s Institute of the Environment & Sustainability.

January is actually at the peak of Southern California’s rainy season when temporary southward shifts in the Pacific storm track, driven by variations in the jet stream, create large rain storms, he said. But, that only happens “a relative handful of times” in any given winter.

“The main reason it hasn’t rained that often on the parade is essentially that it occurs on a single day per year, and even at the peak of the rainy season in Southern California  the likelihood of rain on any given calendar day is pretty low,” he said.

In L.A. County, there is approximately a 10% to 15% chance of experiencing rainfall on any given day in January, he said. In comparison, it has only rained on approximately 8% of Rose Parades, according to information provided by the Tournament of Roses.

But people shouldn’t be two quick to attribute this lower number to special parade day luck, he cautioned.

“The parade itself does not occur all day and night, so for rain to occur during the parade the odds are even lower than for a full calendar day that time of year,” he said.

The coming days will tell if the odds are in the parade’s favor this year.