For a bucolic off-road run, we recommend the Peremohy Arboretum at any time of year. The sizeable arboretum, which also functions as a large park, is located in the southern part of Odessa, adjacent to the Botanical Garden of Odessa University. Paths pass by a wonderful collection of trees, some nicely landscaped sections, and a pond. For running, a loop of the perimeter is ~2.5 km, but one can easily put together 4-5 km on the crisscrossing paths.
Road Access from Central Odessa. From Kulykove Pole Square, use Kanatna St., through the Park of Regional council, and then Marshal Hovorova St. into the Arboretum. For the return, use Shevchenka St., which is a nice wide boulevard.
Park Option: You can also use the Path of Health to get to the Arboretum, or to do a run combining these two great spaces. Use either the multi-use trail or the narrower, more rugged trail on the western edge of the park. Shapansky Ln. is the connector road between the park and Arboretum (~1.3 km).