How Much Does Being Cold Raise Blood Pressure?

Getting cold pushes blood pressure up, and the rise starts within minutes as the body clamps down on blood flow to hold onto heat. Brief or mild chilling usually adds roughly 10 to 15 points to the top number, and a long stay in real cold can add more than 20 in older people. Over a whole winter, average readings run about 5 to 6 points higher than in summer. The answer covers two different things, a short spike while you are chilled and a smaller rise that lasts all season, and older people and people who already have high blood pressure rise the most.¹

How Many Points Cold Adds in the Moment

A blood pressure reading has two numbers. The top number, systolic pressure, is the pressure when the heart beats. The bottom number, diastolic pressure, is the pressure between beats. Both are counted in millimeters of mercury, or mmHg, which this article simply calls points.

Brief cold gives a clear spike. Putting one hand in ice water for a minute raised the top number by about 14 points on average in a large group of ordinary adults.² Cooling the skin with a cold suit raised average pressure by about 10 points.³ Sitting in a room at about 39°F (4°C) raised the top number by about 12 points compared with a comfortable room.⁴

On your own cuff, a reading of 125 can become 140 after you stand in a cold hallway or garage. The bottom number usually rises less than the top one.

Your arm reading may even understate the change. Cold raises the pressure near the heart more than a cuff on your arm shows. In one test the pressure near the heart rose about 13% while the arm rose 2.5%.⁵ That is one reason doctors take cold-related rises seriously even when arm readings look modest.

A single high reading taken right after coming in from the cold is a snapshot of the spike, not of your usual pressure. The spike fades as you warm up, but how fast varies, so a reading a few minutes after coming inside may still be elevated.

Longer cold pushes pressure higher. After 2 hours at about 43°F (6°C), the top number rose about 14 points in young men and about 24 in older men.⁶ Pressure peaks while you are cold and comes down afterward, but it can still sit above where it started.⁷ Even after rewarming from mild cold, the top number stayed about 5% higher in younger adults and about 15% higher in older adults.⁸

Why Your Body Raises Pressure When It Is Cold

Cold on the skin triggers the body’s fight-or-flight nerves, which release a stress hormone.⁹ In response, blood vessels in the skin, arms, legs, gut and kidneys narrow to keep warm blood near the core.¹⁰ The heart then pumps the same amount of blood through tighter pipes, so pressure rises without the heart working faster.¹¹ Over days of cold, hormones that hold salt and water also rise, which can keep pressure up for longer.¹²

The response starts from cold-sensing nerves in the skin and airways, not from a drop in core temperature. So stepping outside in a light jacket can raise your readings even if you never shiver or feel chilled through.

Your face and breath matter too. Breathing cold air and cooling the forehead each raise nerve activity and blood pressure, and a cold forehead raised pressure faster than a cold hand.¹³ Cold air also makes blood platelets stickier, which helps explain why heart risk rises along with pressure.¹⁴

How Much Higher Readings Run in Winter

Readings taken at home average about 6 points higher on the top number and about 3 on the bottom in winter than in summer.¹⁵ At the doctor’s office the difference is about 6 and 4 points.¹⁶ Readings taken during sleep barely change between seasons, likely because people sleep warm.¹⁷ Readings before and after exercise also run higher in winter.¹⁸ A 5-point winter rise is an average across many people, so some rise far more, and unlike a short spike it applies every day for months.

Indoor temperature seems to matter more than the weather outside. Each 10°C (18°F) colder indoors added about 8 points to the morning top number at home.¹⁹ Swings in indoor temperature during the day went along with bigger swings in blood pressure, while outdoor swings did not.²⁰ A cold bedroom or bathroom in the morning can therefore matter more than a cold forecast. Comparing a January reading with a July one can mislead you about whether a medicine is working, so compare readings within the same season when judging changes.

Who Gets the Biggest Rise

Cooling the skin raised blood pressure more than twice as much in older adults as in younger ones.²¹ Stiffer arteries with age seem to make the pressure jump higher.²² Older people’s pressure also rose more slowly in cold but went higher in the end.²³

High blood pressure makes the response stronger. For each degree Celsius colder around them, people with high blood pressure gained about 1 point on the top number, roughly three times what others gained.²⁴ In the ice-water test, people already at 140/90 or above rose about 17 points versus about 13 in those under 120/80.²⁵ Young people with borderline-high pressure had an exaggerated early-morning surge after a cold night.²⁶

Other factors play a smaller part. Women rose slightly more than men, about 15.5 versus 14 points, in the ice-water test.²⁷ Higher body weight, little exercise, and drinking alcohol all went with bigger rises.²⁸ Older people and women were also more sensitive to cold rooms at home.²⁹ A larger response in some Black adults appeared mainly in those with a family history of high blood pressure, not across the board.³⁰

Your own response is fairly stable. People tend to react to cold about the same way when tested years apart.³¹

When a Cold Spike Becomes Dangerous

Heart attack hospital stays rise in the 2 to 6 days after a cold snap.³² Each 5°C (9°F) drop in temperature went with about 7% more stroke admissions.³³ Cold raises pressure, makes platelets stickier, and strains the heart all at once.³⁴

Snow shoveling is the classic danger. Heavy shoveling pushed the top number to about 198 on average, higher than a maximal treadmill test.³⁵

Chest pressure, pain spreading to the arm or jaw, or unusual breathlessness means stop and call emergency services. Sudden one-sided weakness, slurred speech or a drooping face are stroke signs and also need an emergency call. Don’t push through symptoms to finish the driveway.

Push snow rather than lift it, and take small loads. Rest often and avoid shoveling right after a heavy meal. If you have heart disease or high blood pressure, consider a snow blower or help from someone else.

How to Keep Cold From Raising Your Pressure

Keeping indoor temperature steady reduces blood pressure swings.³⁶ Heat the bedroom, bathroom and kitchen you use first thing in the morning, when pressure is most sensitive to cold.³⁷ Avoid going from a warm bed straight into a cold bathroom. Set the heating to come on before you wake, keep a robe and slippers by the bed, and wait a few minutes in a warm room before heavy activity.

Dress for your head and face. Wearing a hat in the cold reduced the blood pressure rise and helped it come back down faster.³⁸ Cover your mouth and nose with a scarf to warm the air you breathe, since cold air and a cold forehead both trigger the rise.³⁹

Medicine may need a winter check. High blood pressure guidelines in Japan now advise adjusting treatment by season.⁴⁰ If your home readings climb in winter, ask your doctor whether your dose needs a change. Don’t change doses yourself, because some people’s pressure drops too low when warm weather returns.

How to Measure Accurately in Winter

Sit in a warm room for 5 minutes before measuring, feet flat and arm supported at heart level. Morning readings are the most affected by a cold room.⁴¹

A useful winter log starts with writing the room temperature next to each reading. Measure morning and evening at the same times, and bring the log to your doctor so they can see winter patterns. Look for readings that climb on cold mornings and settle when you are warm.

Call the doctor if readings stay above your usual target for a week or more. Any reading of 180/120 or higher, especially with symptoms, needs urgent care. Dizziness or very low readings after a medicine change also deserve a call.