Several factors can lead to erratic fluctuations in blood pressure, including medicinal side effects and changes in the weather, according to About.com. Substantial blood pressure variations may also signal serious problems with the kidneys or hormone dysfunction.
Blood pressure generally drops during the summer months and elevates during the winter because blood vessels narrow in lower temperatures, according to the Mayo Clinic. Sudden changes in the atmospheric humidity, precipitation or wind velocity can also cause a temporary spike or decrease in blood pressure levels.
Fluctuating blood pressure may also occur as a side effect of prescribed or over-the-counter medications, as explained by DrDNaturopath.com. Antidepressants and hypertension treatments often cause blood pressure changes. Though hypertension medications are designed to lower blood pressure levels, they do not raise them when they are low, which may lead to erratic readings.
Pheochromocytoma is a tumor of the adrenal gland, as defined by the Mayo Clinic. The condition causes the increased release of blood pressure elevating hormones, which can lead to sporadic episodes of significantly elevated blood pressure results.
Some variation in blood pressure is normal, according to About.com. Throughout the day, levels may fluctuate by 10 to 20 points in response to walking, eating lunch or elevated levels of stress.