Here's a good example of a diurnal owl.
Northern Hawk-owls are a non-migratory, irruptive species with a range that extends around the world in the northern "boreal" latitudes. They are a permanent resident of the boreal Taiga forest where their primary prey consists of voles and Snowshoe Hare. A wide range of other small mammals and birds make up the rest of its diet. Like most owls, they have exceptional hearing and can pinpoint the location of a vole as it tunnels a way under deep snow.
Below are among the best places in the world to see Northern Hawk-owls:
In the US: Northern Minnesota and Alaska
and in Europe: Scandinavia