The dry spell in Boston and Eastern Massachusetts is mainly due to a persistent “high-pressure system” — think clear skies and sunny weather — as opposed to “low-pressure systems” which bring heavy clouds and rainfall, according to Kyle Pederson, a meteorologist for the National Weather Service.

Bring a pattern change from sunny, warm and dry to cloudier, cooler and wet at times. Light rain and drizzle move in tonight with off and on rounds of rain coming i

Friday marks the 23rd straight day without any measurable rain in Boston. It’s the city's longest dry stretch since 1999, according to the National Weather Service.

Unless our weather pattern changes, those areas already excessively dry could be headed into a full-blown drought.