Drought conditions in Maine have worsened in recent weeks after months of fairly steady improvement.

Maine’s coastline from York County through much of Hancock County is under moderate drought conditions as of this week, according to the U.S. Drought Monitor.

All of Washington County and areas further inland, including most of Androscoggin, Kennebec, and Penobscot counties, find themselves under abnormally dry conditions. Slices of southern Aroostook, Franklin, Somerset and Piscataquis counties are also abnormally dry.

Oxford County is nearly designation-free, with very slim portions in the south and west considered abnormally dry.

Sarah Jamison, senior service hydrologist at the National Weather Service in Gray, said some regression isn’t surprising in the warm summer months.

“What we didn’t expect was the precipitation to underperform as it has,” Jamison said in a phone interview Thursday.

While spring and much of June brought a fair amount of rain to Maine, July has been a drier month on average, especially along the southern coast.

“Parts of southern Maine have seen about a third to a half of what you would normally see in the month of July so far,” Jamison said.

Further inland has been slightly wetter. Some of the storms that swept through central and northern Maine this month merely brushed or missed the southern part of the state.

To get back on track, the state needs rain — but preferably not in the heavy bursts that much of Maine has seen as of late.

“Ideally, you want to see a lot of light rain events that can slowly percolate into the ground,” Jamison explained. “In a heavy precipitation event, like a thunderstorm with torrential rainfall, we usually lose around 80% of the water to runoff.”

While a lack of rain is the prime suspect, Maine’s drought problems go deeper. Rainy days can improve surface conditions, Jamison said, but Maine’s groundwater has not fully rebounded.

“That does leave us vulnerable to the surface-level droughts and people could once again have some trouble with their wells and other drought-related impacts as we move forward,” she said.

Surface conditions can fluctuate, but a full recovery for Maine’s groundwater could take some time. Jamison said that would likely require months of above-average precipitation.

“ Until we can really replenish that groundwater, we will be vulnerable to the on-and-off-again surface drought conditions,” she said.