It's one of those days when you just want to stay in bed.

Overcast gray, dreary skies and steady, persistent rain – moderate to heavy at times – are creating a waterlogged situation across the southern and eastern portions of the Big Island, with flooding very likely.

A flood warning was in effect until 1 p.m. for Hāmākua, North Hilo, South Hilo, Puna and Kaʻū as up to 2 inches of rain fell over these areas per hour. It was later upgraded to a flash flood warning as heavier rainfall – up to 10cm per hour – began falling over the same areas.

The island is also under a flood watch until Tuesday as conditions are expected to remain favorable for possible flooding.

Members of the Puna Weather group on Facebook reported light to steady rain this morning in comments to a post by Connie Roark asking what everyone's weather was looking like.

According to later comments, it appeared to be raining heavier around 8am when it started to rain.

About that time, Maggie Bell reported that it was pouring rain in Nānāwale. Brigitte Martinez said it was “very wet in Hilo” at 8:19 a.m., and Renee Whittington summed it up at nearly 8:30 a.m., saying there was “a lot of rain this morning.”

Tom Elliot commented just after 9am that it was pouring in 'Āinaloa and the rain was “increasing really quickly”.

Radar indicated heavy rainfall occurred at 9:48 a.m., causing flooding in the south and east of the island

“A tropical wave with deep moisture and some instability will pass through today and Tuesday,” Puna Weather administrator and founder Harry Durgin wrote in his forecast post at 5:59 a.m. Monday.

This tropical moisture cloud holds the potential for locally heavy rainfall and some thunderstorms, particularly over the Big Island and Maui.

Radar and satellite imagery from the National Weather Service showed a weak low pressure moving into the eastern part of the state this morning, with moderate to heavy showers hitting the south- and east-facing coasts and slopes of the Big Island and Maui.

The main forecast concern remains an extensive area of ​​more than 5 cm of rainfall around this valley, extending into the eastern part of the islands today, combined with a weak trough over the state, increasing instability.

“The low trough area, deep tropical moisture and upper trough area all appear to be aligned, providing the best chance for heavy rain and even a slight chance of thunderstorms on the windward Big Island and Maui from today through Tuesday,” the said The National Weather Service issued its Hawai'i Area Synopis at 10:01 a.m

Flood-prone roads and other low-lying areas could be closed in the event of flooding due to increased runoff and overflowing streams. Urban areas could also experience major flooding and property damage due to rapid runoff.

Leeward Big Island will fare slightly better, with partly to mostly cloudy skies and isolated showers today and Tuesday. West Hawaii could also see locally heavy rainfall, with a small chance of thunderstorms.

The National Weather Service says a cold front will approach the islands and cross part of the state Wednesday into Thursday morning before stalling and dissipating as a new high forms to the north.

This will bring a period of wet trade winds and breezy to locally breezy conditions across the islands later this week and into the weekend.

The forecast for the Big Island remains fairly grim for Wednesday through Friday, with mostly cloudy skies and numerous showers during the day and occasional showers at night in windward areas. The wind-sheltered parts of the island will be partly cloudy with scattered to isolated showers.

Highs range from 82 to 89 degrees and lows range from 67 to 73 degrees. Trade winds will be 15 to 20 mph.