As Air Heats Up, Water Temperatures Stay Cool in Tempe

The forecasts for Tempe, Arizona the rest of this weekend will see temperatures soar above 100 degrees. After showing 94 degree temperatures at the lake today those numbers are expected to soar to 102 degrees on Saturday and 106 degrees on Sunday, when USA Swimming will host the Junior National 5K Championships, the Junior National 7.5k Championships, and the men’s and women’s 5K National Championships at the site.

With safety always at the forefront of these events, especially in the United States. Almost 8 years ago, the memory of open water swimmer Fran Crippen, who died at a race in the UAE still, holds strong for organizers and open water enthusiasts in this country. High water temperatures, officially recorded at 84 degrees and rumored by some to be as hot as 86 degrees, have been blamed as the primary factor in Crippen’s death.

While air temperatures are soaring in Phoenix, as they are wont to do this time of year, water temperatures have remained relatively cool. The low water temperature on Friday was 69.0 degrees (at 3:33AM), and by 1:33 PM it peaked out at 76.0 degrees, according to the WeatherLink Network. Even at its hottest, the water was still below even the coldest pool allowed in FINA competition, which is 77 degrees Fahrenheit (25 Celcius).

USA Swimming is starting all of the races early in the morning, as is tradition at open water events. On Saturday, racing will begin at 8:00AM and should be finished by 9AM. By the race’s end, air temperatures are forecast to be 85 degrees (, and water temperatures will be around 72 or 73 degrees (the water historically has warmed up by between 2 to 4 degrees by that time of morning).

So, while the air temperatures soar mid-day, the low humidity levels in the area, cooler overnight temperatures and the ability of large bodies of water to maintain consistent temperatures better than, say, your local pool, is keeping racing conditions well within safe limits.

Leave a Reply

Notify of
newest most voted
Inline Feedbacks
View all comments
3 years ago

Not all of the races start early, the 7.5K which is used for selecting World JR Open Water teams start at 11 and 11:05 on Sunday respectively.

Reply to  Aquatics
3 years ago

Thanks for the clarification. Do you think it will have an affect on the water temperature and race conditions?

Reply to  Swimmer
3 years ago

I would guess so. With team spots on the line for 7.5 but not the 5 have to wonder why the event order isn’t switched so the 7.5 happens first in the “better” conditions.

Reply to  Aquatics
3 years ago

Actually the water temperature won’t change that much because the overnight air temp is pretty cold this time of year. Water temp increases when there is consistently high temps. These kids might need some sunscreen but they won’t have to worry about water temps as much.

Reply to  Aquatics
3 years ago

They changed the start time to 7:30 for the National 5k and 9:30 for the 7.5k

3 years ago

Just swam in th Masters race That went off around 10:30am. Water temp is beautiful, definitely in that 74-75 area. A HUGE new number of USAS officials and loads of safety crew. Exceptionally well run. A decent enough amount of natural and man made shade available for the number of people.

Thanks USAS and the great local AZ Open Water team.

3 years ago

Does anyone know why ASU hasn’t made their pools available to workout in this weekend?

Reply to  Szk
3 years ago

Did USA Swimming try to rent the pools for people to use?

About Braden Keith

Braden Keith

Braden Keith is the Editor-in-Chief and a co-founder/co-owner of He first got his feet wet by building The Swimmers' Circle beginning in January 2010, and now comes to SwimSwam to use that experience and help build a new leader in the sport of swimming. Aside from his life on the InterWet, …

Read More »