Other facts from our historical weather data: When is summer in McCook?The hottest season / summer takes place in June, July, August and September. Does McCook have a dry season? Yes, the months of January, February, March and November are very dry. Which is the warmest month in McCook? July has an average maximum temperature of 33°C (91°F) and is the warmest month of the year. Which is the coldest month in McCook? The coldest month is December with an average maximum temperature of 5°C (41°F). Which is the wettest month in McCook? August tops the wettest month list with 90mm (3.5 in) of rainfall. Which is the driest month in McCook? January is the driest month with 4mm (0.2 in) of precipitation. No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.