Understanding dew point, heart rate and perceived effort can help runners train smarter in South Florida.
You head out for a run at your usual pace. Within a few miles, your heart rate is higher than expected, your breathing feels harder, and the pace that normally feels comfortable suddenly becomes a struggle.
Sound familiar?
For runners training in Boca Raton and South Florida, this is a common experience, especially during the warmer and more humid months.
But a slower pace doesn’t necessarily mean you’ve lost fitness.
Sometimes, the environment has changed the physiological cost of your run.
Why heat and humidity change running performance
Running generates heat. As exercise intensity increases, your body needs to dissipate that heat to maintain a manageable internal temperature.
One of the main ways it does this is through sweat evaporation.
When the air is humid, evaporation becomes less effective. Sweat may accumulate on your skin without providing the same cooling benefit.
As a result, your cardiovascular and thermoregulatory systems face additional demands.
Your heart rate may increase, perceived effort can rise, and maintaining your usual pace may become more difficult.
This is why running at 8:30 per mile on a cool morning can feel completely different from running at the same pace during a hot, humid afternoon.
The pace is identical.
The physiological demand is not.
What is dew point, and why should runners care?
Most runners check temperature before heading outside. Some also check relative humidity.
But dew point provides another useful piece of information.
Dew point is the temperature at which air becomes saturated with water vapor if cooled without changing its moisture content.
In practical terms, a higher dew point indicates more moisture in the air.
Unlike relative humidity, which changes with air temperature, dew point provides a more direct indication of atmospheric moisture.
For runners, that matters because moisture in the air influences how effectively sweat can evaporate.
A practical dew point guide
| Dew Point | How It May Feel |
| Below 55°F (13°C) | Generally comfortable |
| 55–60°F (13–16°C) | Slightly humid |
| 60–65°F (16–18°C) | Noticeably humid |
| 65–70°F (18–21°C) | Humid and potentially challenging |
| 70–75°F (21–24°C) | Very humid; running may feel significantly harder |
| Above 75°F (24°C) | Extremely humid; additional caution is warranted |
These are approximate comfort categories, not validated thresholds for predicting performance or heat illness. Temperature, solar radiation, wind, running intensity, acclimatization and individual physiology also matter.
In South Florida, high dew points can persist even early in the morning.
That’s one reason why a 7 AM run may still feel demanding despite the absence of intense afternoon sunshine.
Heart rate and pace don’t always tell the same story
Many runners become attached to a particular pace.
They associate it with fitness, progress or the quality of their training.
But pace is an external measure of performance.
Heart rate and perceived effort provide additional information about the body’s response to that workload.
When conditions are hot and humid, your heart rate may rise even when your pace remains unchanged.
During prolonged exercise, cardiovascular drift can also occur, with heart rate gradually increasing despite a relatively steady running speed.
Dehydration, rising body temperature and other physiological factors can contribute to this response.
This doesn’t mean heart rate is a perfect measurement of training intensity. It is influenced by sleep, stress, caffeine, hydration, medications and individual variability.
It means that pace, heart rate and perceived effort should be interpreted together, especially in challenging environmental conditions.
The importance of perceived effort
Rate of Perceived Exertion, or RPE, is a simple way to describe how difficult exercise feels.
For example, using a scale from 1 to 10:
- RPE 2–3: Easy, comfortable running with conversation possible.
- RPE 4–5: Moderate effort, with breathing becoming more noticeable.
- RPE 6–7: Hard effort that requires concentration.
- RPE 8–9: Very hard effort, generally sustainable only for shorter periods.
The exact interpretation can vary by athlete and scale.
For easy runs, the goal is often to maintain a comfortable effort rather than force a specific pace.
If the weather makes your usual easy pace feel moderate or hard, slowing down may be the appropriate training decision.
You are not necessarily compromising the workout.
You may be preserving its intended physiological purpose.
Why easy running is so important
A large portion of endurance training is typically performed at relatively low intensity.
These sessions help develop aerobic capacity, support adaptations associated with endurance performance and allow runners to accumulate training volume with manageable fatigue.
They also provide repeated opportunities to practice movement patterns under relatively controlled effort.
Running faster isn’t always the best way to improve.
Sometimes the most productive decision is to maintain the intended intensity, even if that means accepting a slower pace.
This becomes especially important when heat and humidity add stress to the session.
How should runners adjust their training in South Florida?
There is no single pace correction that works for every runner or every weather condition.
Instead, consider the complete context.
Check the environment. Temperature, dew point, sunlight and wind can all influence heat stress. Wet-bulb globe temperature, when available, provides a more comprehensive environmental assessment.
Use more than pace. Compare running speed with heart rate, breathing and perceived effort.
Respect the purpose of the session. An easy run should remain easy, even when that requires slowing down.
Allow time for heat acclimatization. Gradual exposure can improve physiological tolerance, although it does not eliminate heat-related risk.
Plan hydration and recovery. Fluid needs vary according to sweat rate, duration, conditions and individual characteristics. Avoid both excessive dehydration and overdrinking.
Recognize warning signs. Dizziness, confusion, collapse or other concerning symptoms require stopping exercise and appropriate medical evaluation. Suspected heat stroke is an emergency.
Running performance is more than running mileage
At Costa Performance, we see running development as a combination of aerobic training, strength and conditioning, movement capacity, recovery and informed training decisions.
Strength training can support physical capacity, while individualized planning helps runners balance training stress and recovery.
Understanding how environmental conditions affect performance is another part of that process.
This is also an important educational focus of our CPX Running Team in Boca Raton.
We want runners to understand not only what their watch is showing, but what those numbers mean.
Because training intelligently isn’t about running the same pace under every condition.
It’s about understanding the purpose of the workout and adapting to the demands of the day.
Run with the CPX Running Team
Whether you’re preparing for your first race, working toward a personal best or simply looking for a group that enjoys running, you’re welcome to join us.
CPX Running Team
Saturday group runs at 7:00 AM
Meeting point: Costa Performance, Boca Raton, Florida
All paces are welcome.
Come run with us, connect with other runners and learn how to approach training with greater confidence.
Costa Performance | Strength & Conditioning, Sports Performance & Running Development | Boca Raton, FL
