If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Ostrava: The hottest months are usually August and July, with an average temperature of 18°C, while the coldest months are January and February, with an average of 1°C. The snowiest months in Ostrava are December, January, November and February, with each month seeing an average of 25 cm of snowfall.