Now that September has arrived, we can look forward to fall on September 22nd. You may have noticed that it's actually been feeling more like fall lately.  

But, prepare for summer-like weather to return. In fact, it'll be hotter than a typical Southern California summer.    

We're forecasting our first heat wave of the month to begin this Friday and it'll will continue through Labor Day Weekend and into mid-next week. Inland cities will once again reach the triple-digits.

If you don't have air conditioning, you may find it hard to sleep again because morning lows will also be warm too.  

Normally, average morning lows west of the mountains are in the mid 60s. Many cities will only dip into the 70s.   

This upcoming heat wave will be a bit different than the heat wave in August. 

For one, it won't be muggy this time because we're not expecting any monsoonal moisture or the remnants of a tropical storm to impact our weather. 

Secondly, it won't be as long. The August heat wave lasted between 10-14 days in some inland cities. This next heat wave will last about half that time.  

But, temperatures may be slightly hotter.   

During the August heat wave, highs ran five to 15 degrees hotter than average. This weekend, some daytime highs could run 10 to 20 degrees above average.

Take a look at Riverside’s observed high temperatures for August. 

The city reached triple-digit temperatures ten days in a row.

The last time this happened was back in 2009 from late August to early September. Its longest streak of 100s was 13 days back in 1920.

Overall, Riverside had 20 above-average days in August. Last year, August was hot as well with 19 above-average days. The difference is the hot days were broken up more by some cooler days.   

In Burbank, the heat wave was felt there too.  But, there were many more days in the 90s instead of the 100s.  

Here’s how long the streak of triple digits lasted in other inland cities this past month:

San Bernardino: 16 days

Van Nuys: 9 days 

Ontario: 11 days

Downtown Los Angeles, with an average August high of 84-85 degrees, had nine days of highs in the 90s. The hottest it reached was 98 on August 15. 

Santa Monica, with an August average of 74 had 12 above-average days with lots of 80s for highs and a couple of 90s too.

Long Beach, with an August average of 84, reached the 90s for 9 days and one day when it reached 100.

The strong ridge of high pressure that heated things up in August was in the right position to draw up monsoonal moisture right into SoCal's skies for several days in a row sparking some thunderstorms.  

Several fires ignited, but it's not clear if lightning started any of them.  

So far, inspectors believe a malfunctioning diesel vehicle sparked the Apple Fire. They suspect an arsonist started the Ranch 2 Fire. And the causes for the other fires are still not known.  

This weekend, we won't have the threat of thunderstorms or strong Santa Ana winds to worry about. But, the threat of fires will still increase due to all the dry brush that we normally see in the summer but also the extra brush that hasn't burned in decades.  

Looking back at August, it sure lived up to its reputation as the hottest month of the year in SoCal. 

The heat can and does often last into September. The Climate Prediction Center's outlook for September is calling for a 50-60 percent chance of above average temperatures.