4 minute read
halifax proximity to the atlantic ocean helps fuel the humidity that often makes people uncomfortable, experts say.
ryan taplin
/
the chronicle herald
with environment and climate change canada warning that hot conditions will linger across the province into late saturday, many are seeking out ways to keep cool.
most nova scotians know the feeling.
you step outside expecting a warm summer day but within minutes your clothes are sticking to your skin, you’re sweating heavily and the air feels stifling.
it’s why you’ve probably caught yourself saying, “it’s not the heat, it’s the humidity.”
humidity can make an otherwise nice summer day feel much more exhausting, and while halifax is no stranger to muggy weather, periods of high heat and humidity can quickly become more than just uncomfortable; it can become dangerous.
what is humidity?
simply, humidity is the amount of water vapour in the air, said rachel chang, an associate professor in the department of physics and atmospheric science at dalhousie university.
that moisture becomes important because of how bodies cool themselves.
“we sweat, and when we sweat it’s basically our body’s way to cool,” chang said. “as it evaporates, it cools us down; it takes energy to evaporate the liquid, and that’s how we feel cooler from our sweating,”
however, when there’s already a lot of moisture in the air, that process slows down.
“when the air is completely saturated with water vapour, at some point you can’t evaporate anymore so your sweat can’t evaporate anymore, so then you can’t cool down,” chang said.
that’s also why people often describe humid weather as “sticky” as sweat stays on your skin instead of evaporating.
why is halifax so muggy?
nova scotia’s location plays a major role.
“we’re right next to the ocean,” chang said “there’s a giant liquid water source right next to us.”
but it is not only the atlantic ocean.
chang said a summertime weather system known as the bermuda high often pushes warm, moisture-filled air northward toward nova scotia.
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“we get these southwesterly winds. . . . the air was much warmer and also full of water vapour, and then as it blows more forwards towards us, then it cools down so then it becomes more and more saturated.”
jet skiers zig and zag on lake micmac as they cool off on a hot and humid afternoon in dartmouth on thursday.
tim krochak
/
the chronicle herald
environment and climate change canada meteorologist ian hubbard said the direction of the wind makes a big difference.
“air that’s coming from the north or the northwest tends to be cooler and drier,” he said. “anytime we get a southwesterly flow or westerly flow, even from the great lakes . . . that’s bringing heat from the south.”
he said halifax’s proximity to the ocean also means there’s almost always plenty of moisture available.
“we have a lot of influence from the ocean and the marine environment, so there’s always a lot of sources of moisture around us.”
what is the humidex?
while the temperature tells you how hot air is, the humidex estimates how hot it feels after humidity has been factored in.
“it describes how hot and how humid the weather feels to the average person,” hubbard said. “it’s combining temperature and humidity into just one value.”
a humid day can feel several degrees warmer than the air temperature.
hubbard said humidex levels in the low 30s begin to feel uncomfortable for many people. by the upper 30s, discomfort becomes more widespread, while values of 40 or higher can become dangerous.
why humidity hits harder
nova scotia health emergency physician dr. matthew clarke says the problem isn’t simply the heat, it’s the fact humidity interferes with the body’s natural cooling system. when that cooling process slows down, the body has to work much harder to regulate its temperature.
emergency physician dr. matthew clarke said high humidity makes days feel significantly hotter by slowing the body’s ability to cool.
tim krochak
/
the chronicle herald
in emergency departments, clarke said, physicians see everything from mild heat illness to life-threatening emergencies.
“we would see a fair amount of people who are just generally feeling lightheaded, may have passed out,” clarke said.
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more serious cases include heat stroke.
“we would occasionally see cases caused by the heat things like heat stroke, where people have altered level of consciousness, increased core body temperature or something like that,” he said. “which would be obviously much more worrisome and clearly related to the heat.”
who is most at risk?
anyone can become sick during extreme heat, but some are more vulnerable.
“the people who have less reserve capacity . . . would be the elderly and people with pre-existing medical conditions, particularly cardiovascular and respiratory conditions,” clarke said.
still, he cautioned against assuming healthy people are immune.
“heat can affect anyone,” he said. “i think everyone needs to be careful about it.”
people cool off at maccormacks beach during some hot summer weather in eastern passage in july 2025.
tim krochak
/
the chronicle herald
warning signs
early symptoms of heat exhaustion can be easy to dismiss.
“people tend to notice they’re sweating a lot more, maybe get lightheaded, dizzy, more tired, headache,” said clarke. “those would all be signs that your body’s telling you you’re too hot.”
but if someone becomes confused, agitated or extremely lethargic, the situation may have become an emergency.
“those are all these times you go to an emergency department,” clarke said.
for milder symptoms, he recommends moving somewhere cool, placing cool towels or ice packs on areas like the neck, armpits and wrists, and staying hydrated.
“by the time you’re thirsty, you’re already mildly dehydrated, in most cases.”
community illness, community care
clarke said one of the biggest dangers is that people often don’t realize they are getting sick.
“heat can be one of those ones that can come on kind of gradually and trick people.”
it’s why he said looking out for others is just as important as looking out for yourself.
“it’s really a community illness,” clarke said. “checking in on each other during heat waves is really important.”
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he emphasized that nova scotians should plan ahead for the heat instead of waiting for related symptoms to appear.
“having a plan, being proactive, and then also checking in on each other would be kind of the primary things that i think are important.”
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