Copenhagen, in an oceanic climate zone, exhibits a mild, temperate climate with warm summers and no dry season (although there's more rain at the second half of the year than the first). There's not a lot of difference between the average high and low temperatures, as you can see on the climate charts, but a change of wind direction can alter the conditions drastically. Be prepared for this changing weather.
Copenhagen starts warming up in May. The warmest time to go--June through August--offers average temperatures near 70 degrees. The warmest highs recorded have never hit 90. There is an average of 17 days per month of rain. April-May and September offer the best in off-season weather for those who'd rather not travel in summer. May and June offer the highest mean sunshine hours at 217 and 218.Top Things to do In Copenhagen from Viator
The climate charts below show the historic high and low temperatures and average monthly rainfall for Copenhagen, Denmark.