Our planet has its seasons, just like the year. Day and night ebb and flow, warming and cooling land and ocean in turn. Like a living organism, summer brings back green plants to the Earth's surface, the oceans also bloom, and the polar ice caps retreat. Seen by some of the amazingly sensitive satellites launched by NASA and NOAA in the past few decades, and brought to life by ingenious computer programs, you can experience our planet's seasonal dance as never before.

   Weather also has its seasons, times of year when--other conditions being equal--you can expect certain kinds of weather with greater certainty than at other times. You don't get snow storms in summer, nor East Coast hurricanes in February. But you can experience tornadoes at any time of year, any place in the nation. We're beginning to understand that climate also has its seasons: El Niño years are followed by La Niña conditions, in a great inter-decadal dance, spanning the vast Pacific and bringing dramatically different conditions to Australia, Indonesia, and the Islands, as well as to North and South America. ENSO (The El Niño-Southern Oscillation) also has a direct effect on Atlantic hurricanes: a strong El Niño, weaker hurricanes. La Niña, in turn, allows stronger hurricanes to form and develop.

   This section of the website features information from satellites, as well as patterns discovered by researchers patiently crunching statistics to see what regularities can be found in the natural world. You'll discover why though there is no true tornado season, the May 3, 1999 Oklahoma City tornadoes struck just one day off the most likely day for tornadoes in that city in the whole year! And you'll be able to check out when what kind of weather is most likely to rule the skies in your region.