Weather can very adversely affect driving conditions. In fact, adverse weather conditions like fog have been shown to be the most likely cause of large scale traffic accidents in the United States, where fog and slippery road conditions due to hail, snow, sleet, and rain have cited as causes of some major road accidents involving multiple vehicles.  defensive driving  techniques can help driver cope with these situations and even tell them when it is best to simply pull over and wait for conditions to clear up, as in the case of some dangerous weather conditions.