Blessings: Thunder/Lightning: How Often

Say she'kocho u'gvurato malei olam (on thunder) and oseh ma'aseh v'reishit (on lightning) only once per storm. If you hear thunder over telephone or microphone, you may not say kocho u'gvurato.
Note If the storm clouds clear and another storm comes along, you may say blessings again, even on the same day.