Heat alterations, cancellations continue to impact summer club ultimate.
September 5, 2025 by Charlie Eisenhood in Analysis, News
Each summer, the USA Ultimate adult club season runs from the first weekend in June to Labor Day weekend in early September. Although the Triple Crown Tour season continues to change at the margins, the summer season runs much like it did 20 years ago: teams travel to weekend tournaments with 3-4 games per day played between 8 am and 6 pm. But more than ever before, games are being postponed, rescheduled, or even canceled during tournaments. And that’s not because of thunderstorms or travel woes — it’s simply too hot outside.
A lot has changed in science’s understanding of how heat affects the human body and how seriously it is treated in athletics. Heat stress is the world’s #1 cause of weather-related deaths, but until recently, much of the focus has been on the elderly, the most heat-susceptible population. Modern research is providing more clarity into the risks of exertional heat illness, the type of overheating that can be caused by playing sports1 in hot conditions.
In 2019, in advance of the College Championships in Texas, USA Ultimate revised its heat policy following an outcry from some players about concerns over the possible Memorial Day weekend temperatures in Austin and College Station. The new rules established “heat timeouts” (officially known as hydration breaks) when certain heat thresholds are reached, ramping up to extending the time between points and eventually cancelling games. The guidelines don’t use temperature or heat index; instead, they rely on a measure called the Wet Bulb Globe Temperature (WBGT), which accounts for temperature, humidity, the intensity of the sun, and the wind conditions to determine a more accurate “feels like” temperature.
Even moderately hot temperatures like 90 degrees can be more threatening if they are accompanied by high humidity, because our skin is less capable of evaporative cooling through sweat when there is a lot of moisture in the air. 100 degrees in a very dry place like Phoenix can be less dangerous than 91 degrees in Tuscaloosa. Heat index also captures both temperature and dewpoint (a humidity measure), but WBGT acknowledges that a stiff breeze or overcast skies can help cool you off.
Here, then, are the USAU WBGT guidelines and competition adjustments, unchanged since 2019:
The USAU guidelines, developed in consultation with the Medical Working Group, followed the standards set by numerous high school athletic associations, who followed New Jersey and Georgia in the early 2010s in developing specific heat rules for practices (and, in some cases, games).
“The USAU policy is really well-grounded in the public health guidance,” said former USAU Board President Robyn Fennig, who works in emergency management as the Assistant Director of Hazard Mitigation in the California’s Governor’s Office.
Andrew Grundstein, one of the leading researchers on climate’s impact on human health, agreed, saying that USAU used the “gold standard [WBGT] thresholds” for altering outdoor activity.2
The danger from heat can be hard to sense. “Heat issues are not usually a gradual onset of symptoms; it’s a sudden onset,” said Fennig.
Heat Alterations, Cancellations Becoming Common at TCT Events
Already in 2025, there have been two major disruptions to competition at Triple Crown Tour events. At the Select Flight Invite – East, the last round of play on Saturday was postponed until Sunday morning after the WBGT, measured on site with a Kestrel device, exceeded 90. Then, at the Elite-Select Challenge, the final round — which included the Men’s division final — was canceled after the WBGT crossed above 90. And heat timeouts have become a regular feature of mid-day and afternoon games during summer club tournaments.
Some players aren’t pleased. Complaints about the SFI-East postponement rolled into Ultiworld in July, as players expressed frustration about canceling in what seemed to them to be hot but reasonable conditions. “[It felt like] a pretty pleasant practice day that we’re used to,” said Florida Untied’s Dustin Travaglini. Others said that a 7:30 AM start and a four-round day on Sunday due to the postponement was actually riskier to players than playing in the heat.
Unrelated to SFI, PoNY’s John Randolph wrote an entire blog post about the folly of heat timeouts, calling them the “worst rule in ultimate” with “ridiculously stringent” thresholds. Randolph writes:
The fundamental assumption behind heat timeouts is that adding increased breaks reduces the likelihood of heat-induced injury. In my view, this is flawed for two reasons.
1. The long stretches of exertion that cause heat injury occur during points, not between points. A marathon point is what is more likely to cause heat injury, and heat timeouts do nothing to address that. We already have significant breaks between each point.
2. Teams respond to heat timeouts by playing tighter lines. With heat timeouts or not, top players on any competitive team will play up to their fitness limit in any important game — heat timeouts just mean that they may do that with more points and more rest rather than fewer points and less rest. Either way, the maximal strain on the top players is the same.
Randolph has a point. Ultimate’s gameplay is chunky and features rest breaks between every point, and, on most teams, players only play half of the points in the game. “Ultimate’s not a sport where you have to stay out on the field and play,” said Travaglini. “The average point in ultimate is 35 seconds or so. Then you get more than a minute off.”
But heat is hard to hide from: even if you’re not on the field exerting during a point, high air temperatures and dewpoints can make it difficult to cool off, even if you’re in the shade. But does the existing time between points and points spent on the sideline make heat illness less likely?
Grundstein noted that, in Georgia, there are no heat restrictions on football games, just practice. “Our rules in Georgia are based on the data: we started to see more heat-related problems with WBGT over 82,” he said. “And then even more over 86.” The difference, though, is that games weren’t causing the same kinds of heat problems, even in hot conditions. His theory was that the long stretches of time that players spend on the sidelines during games (as defense rests during offensive possessions, and vice versa) meant that there was enough downtime to avoid complications for heat.3
He said that if ultimate wants to have more sport-specific heat safety guidelines, there needs to be real research into the effects of heat at ultimate tournaments. “It sounds to me like ultimate frisbee is way understudied when it comes to heat-related stress,” he said.
Possible Changes to the USAU and WFDF Heat Policies
Regardless of any marginal changes to the WBGT thresholds for alterations and cancellation, ultimate organization’s heat policies may not be optimal for serving their purpose: making sure players are able to cool off in hot conditions.
Heat timeouts — the most commonly used intervention — adds three minute breaks in the middle of both the first and second halves. But recent research on rugby players showed that a longer halftime (going from 12 to 20 minutes) had a much bigger cooling impact than adding 3-minute quarter breaks. Currently, USAU and WFDF halftime lengths are 7 minutes; it may be better for heat safety to extend halftime to, say, 13 minutes instead of adding heat timeouts during play, especially given ultimate’s existing stoppages between points.
The latest research also suggests the use of misting fans and ice towels to help players cool off: misting fans have been shown to reduce body temperature even in hot, humid conditions. Shade tents can help provide respite from the sun. Supplying these heat mitigation tools at large-scale tournaments and suggesting to teams and local TDs to bring ice water coolers with hand towels could also help.
Perhaps the bigger issue is tournament scheduling. Hosting TCT events in hot, humid summer climates (like, for instance, in Fredericksburg, VA, where SFI East was held and average July temperatures reach 90 degrees) is more likely to cause heat issues and frustrating schedule alterations. It’s also more dangerous for teams from cooler parts of the country to travel to hotter ones to play tournaments, as the body takes more than a week to acclimatize to local weather conditions.
“You could use climate data to find optimal locations…but you always have to be prepared for a crazy heat wave even in locations that are normally mild like Seattle,” said Grundstein.
Tournament organizers may also need to be prepared to play more games outside of the hottest part of the day, scheduling games for the morning and then not playing again until the late afternoon and evening. Lighted fields may become increasingly necessary to accommodate mid-day breaks.
And what about turf vs. grass? Many ultimate players feel that playing on turf in the hot summer sun is substantially hotter and more taxing than playing on grass, though studies have found that, although the playing surface is much hotter, the local WBGT is largely unaffected and playing on turf, then, doesn’t impact human heat stress.
Other sports are dealing with the same heat problems as ultimate. A recent NWSL match was delayed 3.5 hours due to extreme heat in Kansas City with kickoff scheduled for 3 PM local time. There are already concerns about next year’s World Cup in North America after the Club World Cup this summer was plagued with hot weather conditions across the venues in the United States.
Of course, it’s easier for massive international sporting events to schedule games to avoid the hottest parts of the day. Ultimate’s long tournament days, often in full sun in the summertime, suggest caution. “Because I see the worst of these things when players get heat stroke and have devastating problems that affect them the rest of their lives, I tend to be conservative,” said Grundstein.
or doing manual labor or other outdoor tasks ↩
Note that a 90 degree measurement in WBGT is not comparable to what you might think of a 90 degree temperature. They’re different scales. ↩
Other states, like South Carolina, will cancel games, not just practices, for a WBGT reading over 90. Some southern states also use a higher threshold for cancellation (92 is most common) since weather is hotter on average, so heat tolerance among the local population is higher. ↩
