Why have wildfires been erupting across the East Coast this fall?

Authorities in multiple states across the Northeast battled wildfires Monday as conditions remained ripe for blazes to erupt and spread quickly despite some areas receiving their first rainfall in over a month.

In New Jersey, firefighters fought the Jennings Creek wildfire raging along the New Jersey-New York border, which had grown to 3,500 acres and was 20% contained, officials said Monday evening.

Over the weekend, New York state parks worker Dariel Vasquez, 18, was killed by a fallen tree while he was battling flames in Sterling Forest in Orange County.

The fire was one of several that burned throughout the weekend in New Jersey, New York, Massachusetts, Pennsylvania and Connecticut – the result of historically dry conditions across the region that were only slightly improved by the quarter-inch of rain that fell Sunday night into Monday.

Here is what we know about the wildfires, their cause and whether more rain is forecast:

Why are there wildfires in the Northeast?

The Northeast experiences wildfires every fall season, and the majority of blazes are attributed to human causes such as campfires, burning debris and cigarettes. However, what has meteorologists and state officials especially concerned this year is a record-setting dry spell in the Northeast that is fueling a sharp rise in wildfires and their explosive growth.

The Northeast, like the vast majority of the country, is suffering from abnormally dry conditions, and many states are experiencing severe and extreme drought, according to the U.S. Drought Monitor at the University of Nebraska-Lincoln.

What states and cities have gone without measurable rain?

On Sunday evening and into the overnight hours, some showers brought the first rain in months to parts of the Mid-Atlantic, including New York City, where 0.17 inches of rain fell – the only rainfall the metropolitan area has picked up since late September.

In New Jersey, the dry spell has smashed records in multiple cities. As of Friday, Trenton had gone 41 days without measurable rain – the prior record was 36 in the fall of 1924. Newark has gone 40 days without measurable rainfall, flying past the previous record of 26 days set in the spring of 1949.

Similarly, Philadelphia went at least 40 days without rain, breaking the record of 29 days set in 1874.

Both New Jersey and Delaware reported their driest October on record this year, according to the National Weather Service.

Are wildfires common in the Northeast?

Wildfires torch thousands of acres of land in Northeast states each year, though they are most common in the spring.

In New Jersey, 1,500 wildfires damage or destroy 7,000 acres of forests annually, according to the state's forest fire service. State officials say that while the high season is in the spring, leaves in the fall months add extra fuel and lead to more blazes, especially when the region is experiencing unusually dry conditions.

In New York, where thousands of acres of land are engulfed in wildfires each year, the state says that 47% of all wildfires occur from March 15 to May 15.

About 15 wildland fires are reported each October in Massachusetts. This year, the month’s total reached 200, an increase of about 1,200%. The spike, according to the state's Department of Fire Services, rivals "the monthly numbers usually seen in the traditional early spring brush fire season."

Just last week, Massachusetts officials raised the drought level to "significant" and "critical" throughout the state. Fire authorities reported on Saturday that firefighters were battling at least 175 blazes.

What regions have been under alerts or warnings about wildfire risk?

Areas from Washington, D.C., to New England had been under advisories in the past week about heightened risks of wildfires.

On Saturday, for example, there were red flag warnings in place in the New York metropolitan area, Connecticut, Rhode Island and Massachusetts as strong winds, relatively low humidity and dry conditions endured, the National Weather Service said. Most of those warnings had expired by Sunday night, but officials urged residents to not let their guard down and to exercise caution with potential ignition sources such as machinery, cigarettes or matches.

When will the drought end in the Northeast?

Meteorologists say it's unlikely more rain will alleviate the widespread dry conditions across the Northeast.

Storms are forecast to barrel toward the region over the next two weeks, potentially bringing rain to New York City and southern New England; however, the showers will be limited and are not projected to soak the dry soil for any meaningful period of time.

"While that more active pattern will bring some opportunities for rain this week, it does not guarantee that every spot will get enough rain to keep the fire potential at bay," said John Feerick, a meteorologist with AccuWeather. "Some locations could go at least a full week without a drop of rain."

On Thursday, a front from the Midwest is expected to arrive in the Northeast and it could bring some tropical moisture with it. But, it won't be the large storm that the Northeast needs for sustained relief, Feerick said.

Contributing: John Bacon and Jorge L. Ortiz; Amanda Wallace and Manahil Ahmad, Bergen Record; William Westhoven, Daily Record; Ken Serrano, Asbury Park Press

(This story has been updated to add new information.)

This article originally appeared on USA TODAY: Wildfires have been erupting across the East Coast. Why?