Bradycardia can be caused by: 1  Changes in the heart that are the result of aging.  Diseases that damage the heart's electrical system. These include coronary artery disease, heart attack, and infections such as endocarditis and myocarditis.
Portland Weather In May. The highest recorded temperature in May for Portland for the past 70 years was 100 degrees Fahrenheit, most recently measured on May 28, 1983, and the normal high is 67.
Like many of Oregon's large cities, Portland's climate can be unpredictable. September is traditionally one of the city's warmer and drier months, with average daytime highs of about 74 degrees Fahrenheit and overnight lows in the mid-50s. September's precipitation levels average less than 2 inches, with the first half of the month usually much drier than the second.