The weather in Philadelphia has a dry record and warm Halloween forecast

The day after Philly set a record for most consecutive days without rain, it seemed almost certain Tuesday that this would be the driest October — and driest month — in a city with one of the oldest official weather databases in the country.

As an addendum, it is also possible that the temperature will reach its warmest on what is expected to be a dry Halloween on October 31st, an honor now held in 1946 when the temperature rose to 82 degrees.

With Thursday's forecast high of 80, “we're going to be close,” said Raymond Kruzdlo, a meteorologist at the National Weather Service office in Mount Holly. Kruzdlo also happens to be the office's senior hydrologist.

He is aware that a while has passed between flood warnings.

Monday marked the 30th consecutive day without measurable precipitation in Philadelphia, which has been keeping records since 1872.

About the Philly drought record now in the books

The previous record for consecutive days without precipitation in Philadelphia, 29, was set in 1874, not long after the founding of the nation's weather service in 1870, an outstanding achievement of the Ulysses S. Grant administration.

(The investigator noted the year 1874 Streak that ended on November 8th, but only in passing. It seemed like more room was being given to a six-week losing streak in Alabama.)

Philly did see a trace of rain on Thursday, but the rainfall total did not reach the 0.01 inches needed to break the streak that began Sept. 29.

New Jersey has declared a drought warning, a step Pennsylvania has not yet taken.

October is often dry in Philly, but this one set new standards

Philly's driest months on record – with a total of 0.09 inches of rainfall – occurred in 1963 and 1924. Not surprisingly, both months were in October.

October is a transition month for Philadelphia between the rainy summer and the more consistent precipitation that comes with more organized storms that accompany nor'easters and cooler weather.

The main sources of rainfall in October were remnants of tropical storms and precocious nor'easters.

Neither source has been reported here recently, and as of 11:59 p.m. Thursday, forecasts say this will be the first month on record that Philly has not recorded any measurable precipitation. That would of course be a record for October.

The dry air contributed to the rapid cooling after sunset and a number of cool mornings.

On Monday, several areas outside the city recorded readings below freezing and even above 20 degrees, although city heaters helped keep temperatures above 40 degrees at the heat-resistant Philadelphia International Airport. The weather service declared the “growing season” over in much of the region.

The dryness is due to persistent high pressure or heavier air over the east, which used its descending currents to ward off rain. In order for water vapor to condense into raindrops, the air must rise.

In fact, the Northeast is cut off from the Gulf of Mexico, a major source of moisture.

The parched conditions also contributed to the fronts being as dry as the dirt as they passed through the region, forecasters said.

When might it rain again in Philadelphia?

Showers are possible at least Friday morning and possibly very late Thursday evening, said Michael Silva, senior meteorologist for the weather service.

And Kruzdlo said the pattern appears to be on the verge of weakening. High pressure is expected to ease over the weekend.

The government's Climate Prediction Center says there is a chance of slightly above normal rainfall during November 5-11.

The pattern looks “more ephemeral,” Kruzdlo said. He said a system approaching the region next week may be able to remove some of the Gulf moisture.

However, he does not expect to issue flood warnings.

Should the region finally experience rain events, he said, “They don’t look like big rain events.”