Earth Log

Earth Log: September cooking like it's August

September heat feels worse than August heat. How many times have I heard that this month? Couldn't be true, right?

August and September seem actually pretty close this year. And the return of dirty air hasn't made it any less miserable.

So far in September, Fresno is averaging 84.3 degrees -- the figure is the average of temperatures taken throughout the days. That's more than six degrees above normal. Last month, Fresno averaged 84.4 degrees.

In Fresno, the highest-ever-recorded average temperature for September was 81.3 two years ago, the National Weather Service records say. That record could be challenged this month.

The San Joaquin Valley's air seems to be reacting to the heat. By Sunday, the air had already exceeded the federal eight-hour standard on 11 days.

Remember August? There were only 14 bad days -- meaning there were more good days than bad for the first time since I started following these numbers in the 1990s. 

On Saturday, the Valley nearly had a one-hour ozone exceedance in northwest Fresno, missing by only one part per billion. Violations of the one-hour or peak standard is the reason the Valley is on the hook for $29 million in extra fees. 

Could the ozone problems continue? Yes.

Last year, there were seven bad days in October, the last of which was Oct. 27. In 2011, there was an ozone exceedance on Halloween.

In 2010, there were exceedances of the ozone standard in November.

While we're on the subject of heat, Fresno averages 36 days of 100-degree heat a year. If the mercury passes 100 today, it would be the 49th of the year.

The record is 63, set in 1984, according to the Weather Service.