For the same reason that in the winter the weather people tell you the temperature, but then are sure to include the windchill factor (which makes it sound worse). In the summer they tell you the temperature and be sure to include the "real feel", which includes the heat index and makes it sound worse. Arguably, in the winter there's still a heat index and in the summer a wind chill, but that would make the news sound good, and mess up the whole strategy.
Bad news sells. Mostly it's totally made up BS. Global warming is another made up tragedy to distract us from real issues like wars, poverty, wealth disparity, care for the elderly and mentally ill, etc.
Bad news sells. Mostly it's totally made up BS. Global warming is another made up tragedy to distract us from real issues like wars, poverty, wealth disparity, care for the elderly and mentally ill, etc.