Since January, more than 3,100 flash flood warnings have been issued nationwide — the highest year-to-date total since tracking began for alerts in 1986.

A flash flood warning was in effect in New York City until 9:45 p.m., and New Jersey Gov. Phil Murphy declared a state of emergency. Middlesex, Morris and Somerset counties remained under a flood warning until 7:15 a.m. Tuesday.

New Yorkers in basement apartments were told to be ready to leave and New Jersey’s governor declared a state of emergency after heavy rains in the northeast caused flash flooding, officials said

According to the Weather Channel, a flash flood emergency is a rare alert issued by the National Weather Service that serves as a signal that you’re likely in imminent danger. A flash flood warning is issued by the NWS when flash flooding is either already happening or expected to develop soon.

Torrential rains flooded basements, backed up sewers and even impacted the Avera Marshall hospital campus on Friday night. Today, city officials declared a state of emergency, and said they were working with Lyon County to respond to localized flooding.

Here's what to know about flash floods, emergency systems and how to stay safe as Florida is in the Atlantic hurricane season.

Severe flash flooding across the tri-state area on Monday caused major subway delays and road closures across the Big Apple and pushed New Jersey to declare a state of emergency. All five boroughs and Nassau County were under a flash flood warning through midnight, according to the National Weather Service.

Two massive disasters this year — the Texas floods and Los Angeles firestorms — are leading some to grapple with the question of how to get officials and the public to care and take action.