Downpours are expected in Zealand and Funen on Thursday afternoon and evening, reports broadcaster DR.
The rainy weather follows a July which fell two days short of becoming the first for 38 years in which no summer days were recorded.
August seems unlikely to offer much improvement on the damp squib offered up last month, according to the report.
According to a risk assessment released by DMI, thunderstorms are expected over the islands of Zealand, Lolland-Falster, Bornholm and most of Funen between 3pm and 8pm on Thursday.
“We have warm air in the south and a cooler air mass in the northwest, and that will generate cells that can give strong rain and thunder during the afternoon,” DR weather presenter Christian Cherry told the broadcaster.
Up to between 15 and 25 millimetres of rain could fall within 30 minutes in localised areas, enough to create a risk of floods in low-lying areas, basements and on road surfaces and reduced visibility, according to the report.
Grey weather is forecast for the country during the rest of the day, including prior to the storms.
“During the morning there will be some persistent rain, which is beginning to reach western parts of Zealand and Lolland. You could say it will be a nice day for people who love rain,” Cherry said.
While DMI's weather warning only applies to the eastern part of Denmark, Jutland is also unlikely to remain dry, reports DR.
“The rain currently over Jutland will move away quickly. There is a fresh wind just now, which means the rain will move on quickly, but they will get rain,” Cherry said.