Rain and even thunder are forecast to affect New Year’s Day festivities at the Rose Parade in Pasadena, where crowds have not faced the kind of weather that can complicate viewing along the parade route, organizers and meteorologists said.

According to the AccuWeather forecast cited by the Associated Press, forecasters have increased the chance of rain for the Rose Parade, which has been dry for 20 years. AccuWeather meteorologist John Feerick said, “It’s looking like a wet one,” and added that rainfall may not last the whole time. He also said “there could be some pretty good downpours” and that “A rumble of thunder or two is not out of the question.”

Organizers said they are planning for the forecast without dramatically changing the event. Candy Carlson, communications director for Pasadena Tournament of Roses, said organizers are making only small changes for the parade ahead of the Rose Bowl college football game. She said the tops will be up on convertibles carrying grand marshal Earvin “Magic” Johnson and other VIPs.

Officials also described how viewing arrangements could be tested by overnight conditions. People were allowed to arrive Wednesday to secure spots along the nearly 6-mile (10-kilometer) route in Pasadena, but the AP report said overnight rain predictions could make the waiting period miserable. The Associated Press said the two-hour parade starts at 8 a.m. Thursday and is typically attended by hundreds of thousands, with millions more watching on national television.

Across the country, attention is also on New York City’s Times Square celebration and the midnight ball drop on New Year’s Eve. Forecasters predict temperatures in the low 30s Fahrenheit (around zero degrees Celsius) and snow flurries as hundreds of thousands of people gather for the event.

AccuWeather meteorologist Jesse Ferrell said the midnight temperature in New York could be “the coldest since the cusp of 2017 and 2018.” The Associated Press report also noted other city forecasts that could bring wintry conditions or rain around New Year’s celebrations, including rain possible in Las Vegas and cold conditions in Nashville’s Big Bash, with New Orleans expecting mid-40s Fahrenheit temperatures for a free concert and fireworks along the Mississippi River.