Blood pressure: Is it affected by weather?

Can weather affect blood pressure? I've noticed that my blood pressure is harder to control in the winter.

- No name / Michigan

Mayo Clinic hypertension specialist Sheldon Sheps, M.D., and colleagues answer select questions from readers.

Answer

Yes, weather can affect blood pressure. Blood pressure generally is higher in the winter and lower in the summer. Why? Cold temperatures cause your blood vessels to narrow (constrict) — which increases blood pressure because more pressure is needed to force blood through a narrower space. Other possible causes of higher blood pressure are weight gain and decreased physical activity in winter.

However, it doesn't take a big cold snap to raise blood pressure. Seasonal blood pressure changes also are found in climates where temperatures may change only a few degrees from summer to winter. In fact, a five-year analysis of the electronic health records of 444,000 adults with high blood pressure in the United States and its territories found that high blood pressure was less controlled in winter than in summer in all cities, from Anchorage, Alaska, to San Juan, Puerto Rico. The implication from such studies is that it may be necessary to adjust high blood pressure medications in some people to continue to control blood pressure in different seasons.

If you have questions about how weather may affect your blood pressure, consult your doctor.