We all know that last summer broke a slew of records in Arizona: 55 days of 110 degrees or hotter, 133 days hotter than 100, just 4.2 inches of rain and the hottest July in Phoenix history.
But, we didn’t see the hottest Arizona day on record last summer — and, it turns out, Phoenix isn’t even, technically, the hottest place in the state. That’s according to Arizona’s state climatologist Erinanne Saffell. The Show spoke with her more about it — and more heat records, facts and figures you might not have heard of — beginning with the hottest place in the state.
Full conversation
ERIANNE SAFFELL: Where is the hottest location in Arizona? We're hot, but the hottest location ever recorded was 128 °F at Lake Havasu City. And that happened in 1994.
LAUREN GILGER: My goodness, that's a crazy temperature. What were the conditions that led to that? Do we know?
SAFFELL: Well, these heat waves that we can get in June, we can get really hot temperatures in June. And you know, if we go back historically, we can look at some of those heat waves that have happened before. Like in 1896 there was another really hot condition, hot heat wave in June. Parker, Arizona had four days in a row that temperatures range from 123 degrees to 126 degrees. So we can get really hot in Arizona.
GILGER: We can, and it's interesting that those records because we're talking about breaking records all the time right now in the Valley, right. But those records you're talking about are from sometimes 100 years ago or more, sometimes 20 or more years ago. It's, it's interesting that they are not all happening right now, right?
SAFFELL: We do have some records that still have not been broken. But unfortunately, well, fortunately, I guess is a better way of looking at it. Our record that we set last July, I think we all remember that with Phoenix being the hottest city in the United States for a month. We had that 102.7 degree average temperature last July looking at this July, I was making sure, watching carefully to see what would happen this July and they were neck and neck. Last July, this July, the Phoenix temperatures for the first two weeks of July were neck and neck. Fortunately, we had some thunderstorms coming in these last couple of weeks and it looks like we won't be breaking that record last year.
GILGER: Wow. OK. So that's a bit of good news. Let's talk a little bit about how it is that you measure the heat, right? Like there are some technical instruments that you use to do this describe the process.
SAFFELL: You know, really, we're measuring the temperature that happens at the hottest time of the day. We call that the maximum temperature and that usually happens around three or four in the afternoon. It depends on the time of year. And then we measure what's called the minimum temperature, the nighttime temperature, which actually really happens right around sunrise. That's the coldest time of day, typically.
And so we look at the maximum temperature, we add them together, the max plus the min, we divide by two that gives us what's called the average temperature. And so that's one way to kind of see what's going on, kind of have a standard line to check things. But we also look to see what's happening with our maximum temperatures. Are they getting hotter? Are our nighttime temperatures, minimum temperatures, what's happening to those? Are they getting hotter? So we pay attention to all of that.
GILGER: And that's one of the big ones, right? The nighttime temperatures are also setting records right now.
SAFFELL: Right. So daytime temperatures, yes, we're, we're seeing in the Phoenix area, we're getting 110 degrees or higher more often during the day. And this is happening when we're dealing with temperatures, June, July, August. So in summer, the hottest time of the day. But what we're seeing is that the nighttime temperatures are not cooling off when we're looking at the parking lots and your house and sidewalks, those are acting like a solar oven and they're holding on to that sunlight, holding on to it and releasing it very slowly at night. So our nighttime temperatures are actually increasing at a greater rate than what the daytime temperatures are doing.
GILGER: And those certainly are increasing right. So, talk a little bit about where we measure heat. I know there were lots of questions that came up last summer about all of these record temperatures being measured and recorded at Sky Harbor International Airport. Like that's the official temperature measure that we read on our weather newscasts, right? Like there's a lot of cement, it's hot there. Do you pick and choose the places where you measure the heat?
SAFFELL: Yeah, I think it's important to understand that I look at all of these weather stations that are all across the state and the Southwest and we're seeing these trends. So when you're looking at not just what's happening at the Phoenix Sky Harbor Weather Station, but you're seeing it happening in Winslow and Flagstaff and Prescott, that gives you some sense that you're seeing that longer trend. It's not just that one weather station that's having those issues.
GILGER: So you can measure the trend more generally across the state and see that it's still true. Talk a little bit about some of the heat measures that do not work in Phoenix. I know we hear a lot about the heat index. That's, you're saying not applicable here in a real way.
SAFFELL: Right. We need to pay attention to how hot temperatures can get here in Arizona. We need to keep people safe from the heat. But a lot of the other places in the country use something called the heat index. We don't necessarily use that in Phoenix because really it's a measure of what the temperature feels like based on how much moisture is in the atmosphere. So the relative humidity comes into kind of figuring out the heat index and, you know, our relative humidities are really, really low. We're really dry, we're in a desert. So it doesn't really work for us here in the Phoenix area.
GILGER: OK. So, final question for you. You said that so far this July is not going to break the records that last July broke few. But are we past the worst of the heat here? I know it stays hot here for another at least two months. Right.
SAFFELL: Absolutely. So, I kind of look at those things as well. How often have we had 118, 119, 120? What does it look like through our period of record? And it looks like we might be done with 118 degrees in the Phoenix area, but we could absolutely hit 117 and there's, you know, there's no doubt that some, at some August, we might get 118, but hopefully we're done with those.
We like it when it gets a little bit cooler, but we're still not over everything yet. So please pay attention. We're still going to get 110 degrees and, and so on.
GILGER: So, are we also seeing the length of the hot time of year? The hottest times of the year lengthen? I mean, like, are we seeing it stay hot through September now? October?
SAFFELL: Well, it's been hot. So if we look at like last October, November, December, and we're looking at what's happening statewide, it was really hot last year. And so, yeah, we're seeing temperatures kind of staying warm, but we will make that break, the monsoon season will kind of cool off. We'll come to our, what we would call fall and it will happen at some point.
GILGER: All right, it will happen a promise from the state climatologist Erianne Saffell.
