Phoenix weather: We just had the hottest November ever. And 2017 could be the city's hottest year

Phoenix residents, you can say you were here when weather history was made in November. And if current trends continue, even bigger records could fall.

November 2017 was officially the warmest November on record for Phoenix and there is a pretty good chance that 2017 will go down as the hottest the city has seen since records were kept starting in 1895.

According to some serious number crunching Thursday at the National Weather Service office in Phoenix, there is a 47 percent chance that 2017 will finish atop the Phoenix hot list. Even if December bucks the recent trend of warm months, there is a 96 percent chance that 2017 will wind up in the Top 3 warmest years and a greater than 99 percent chance it will be in the Top 10.

And if high temperatures don’t impress you, the city is also deep into a dry spell that just reached 100 days. There has been no measurable rain at Phoenix Sky Harbor International Airport since Aug. 23.

Hottest year ever?

Through November the average temperature for Phoenix (combining the average high and low and dividing by 2) was tied with 2014 for the hottest on record, according to the National Weather Service. Rather than wait for Dec. 31, Phoenix NWS meteorologists put together a detailed analysis to determine the likelihood of this year coming out on top.

Using the Climate Prediction Center’s outlook for December as a starting point, they performed a million computer simulations to determine the probability of this year being the warmest.

Meteorologist Paul Iñiguez said they started performing that analysis because it was nearing the point in the year when people begin looking at the temperatures and start asking where things stand.

“We inevitably were going to get the question of how this was going to rank out,” Iniguez said. “I feel we were at the point where we could do a little bit of analysis and leverage the information that (the National Oceanic and Atmospheric Administration) was putting out.”

The NWS analysis shows that Phoenix’s average temperature has been warming at a rate of over a half degree (Fahrenheit) per decade. Eight of the 10 hottest years on record have occurred since 2000.

Iñiguez said there are two main reasons behind the trend.

“Urbanization, the urban heat island, is going to be a big driver,” Iñiguez said. “The regional signal we see, and the much larger signal we see, is the changing climate. This isn’t theoretical stuff, we measure it. We can see temperature are going up.”

Warmest November

Next let’s take a look at what happened in November.

A persistent area of high pressure hovered over the state and kept temperatures above normal throughout the month.

• The average high for the month was 82.9 degrees, the warmest ever and 7.4 degrees above normal for that statistic. The previous record was 82.3 degrees in November 1949.

• The average low temperature was 59.5 degrees, also the warmest ever and 6.8 degrees above normal. That tops the record of 58.3 degrees in 2007.

• The average temperature for the month was a record-setting 71.2 degrees, 7.1 degrees above normal. The previous record of 70 degrees was set in 2007.

Iñiguez said the unusually warm temperatures fit with recent trends of Phoenix seeing warm weather for much of the year.

“It’s kind of a broadening of the heat season,” Iñiguez said. “We don’t have summer getting hotter and hotter, it’s not hitting 125 or anything. But the 90s are hanging on longer and the 80s are hanging on longer.”

An unusually dry fall

Even with a dry spell at 100 days and counting (the current forecast does not include rain), the city has a way to go before it approaches records. The longest dry streak in Phoenix was a span of 160 days that ended on June 7, 1972.

Part of what makes the current streak so unusual is the time of year it’s occurring. There has been just one other meteorological fall (the months of September, October and November) when there has been no measurable rain. That was in 1938.

The current dry spell would have to make it through a couple of what are often some of the city's wettest months to threaten the record.

Iñiguez said there is one bright spot in the current dry spell. What happens in fall doesn’t predict what will happen in winter.

“We’ve had very dry falls followed by very wet winters and very wet falls followed by very dry winters and everything in between,” Iñiguez said. “Just from a statistical standpoint it doesn’t tell us much.“

But, Iñiguez said, the things that do offer some predictive value, conditions in the oceans and atmosphere, don’t offer much hope.

“That would tend to tilt our odds toward the winter being drier than usual,” Iñiguez said.