It's a heatwave, and we need to take things seriously!!
Wet Bulb warnings:
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So what happens if it rains at 28C, which is what is supposed to happen later today?
Rain at 28 °C is one of the trickiest and most dangerous heat‑wave situations because rain pushes humidity toward saturation, which can drive the wet‑bulb temperature sharply upward even if the air temperature doesn’t rise. This is exactly the kind of scenario that makes heatwaves in Quebec feel suddenly oppressive.
Here’s what actually happens — and why it matters.
🌧️ 1. When it rains at 28 °C, humidity often jumps toward 90–100%
Rain adds moisture to the air and reduces evaporation.
When humidity rises:
Sweat stops evaporating efficiently
The body loses its main cooling mechanism
Wet‑bulb temperature climbs toward the air temperature
This is the mechanism behind dangerous humid heat.
As explained in heat‑stress guidance, wet‑bulb temperature rises as humidity increases because evaporation slows down, reducing the body’s ability to cool itself .
🌡️ 2. What the wet‑bulb temperature becomes at 28 °C with rain
Let’s estimate:
Scenario A — Before rain (65% humidity)
WBT ≈ 24–25 °C
→ Caution / High stress for vulnerable people
Scenario B — During rain (90–100% humidity)
WBT jumps to 27–28 °C
→ Danger zone
This matches published heat‑stress categories where wet‑bulb temperatures in the 24–28 °C range correspond to high to dangerous heat stress, requiring reduced activity and careful monitoring .
If humidity hits 100%, WBT ≈ air temperature → 28 °C WBT, which is a level where exertional heat illness risk increases sharply. WBGT‑based guidance shows that WBGT values above 28 °C correspond to red‑zone danger, where only light activity is recommended and heat‑stroke risk rises dramatically .
🔥 3. Why rain can make heat feel worse, not better
Rain cools the air a little, but it also:
Eliminates evaporative cooling
Makes the air feel “heavy” and suffocating
Causes sweat to sit on the skin
Increases risk of dizziness, nausea, and heat exhaustion
Medical guidance notes that high humidity traps heat inside the body, increasing risk of dehydration, heat exhaustion, and heatstroke even when temperatures are not extremely high .
So a rainy 28 °C can feel more dangerous than a dry 33 °C.
🧭 4. What this means for you today
You’re at the start of a heatwave, and rain at 28 °C is a classic “hidden danger” moment.
Expect:
Sticky, oppressive air
Sweating that doesn’t cool you
Higher heart rate
Fatigue or mild headache indoors
Outdoor exertion becoming risky
If you’re in a home without strong AC, this is when rooms start to feel “stuffy” and uncomfortable.
🛡️ 5. How to protect yourself during rainy heat
Avoid outdoor exertion during or right after the rain
Use fans to increase evaporation (they help even in humid air)
Drink water steadily
Take cool showers if you feel overheated
Keep blinds closed to reduce indoor heat load
Check on older adults or anyone with heart/lung conditions
🔍 Want me to calculate the exact WBT for your location when the rain starts?
Just tell me:
the temperature
the humidity (or I can estimate based on typical rain values)
I’ll place it on your heat‑risk scale and tell you how dangerous the next few hours will be.
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Gemini AI:
I am trying to become familiar with the notion of Wet-Bulb Temperature, and discomfort in a heat wave. It would be helful if I had a visual temperature/humidity graph with discomfort to danger areas shaded in. Either from you, or as a site I could visit...
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USA Occupational Health:
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