Mark Twain once said he counted 136 kinds of weather in a single New England day. If he were around today, he’d probably be tuning in to his local TV station and going online for help with the task.

Twain would have plenty of company. A nationwide survey just out from the National Center for Atmospheric Research (NCAR) found that nearly nine in 10 American adults check weather reports regularly. That adds up to about 300 billion forecasts annually.

The study is the first to comprehensively assess the public’s perception, use and value of forecasts. It appears in the June issue of the Bulletin of the American Meteorological Society. The work was funded by the National Science Foundation and National Oceanic and Atmospheric Administration.

The landing of space shuttle Atlantis has been postponed until tomorrow morning at the earliest* because of bad weather at Kennedy Space Center in Florida.

Atlantis had two landing opportunities at Kennedy today, but both were waved off this morning because of elevated crosswinds, a low cloud ceiling and nearby thunderstorms, all three of which fell outside NASA's parameters for a shuttle touchdown.

The first of four landing opportunities tomorrow is at 9:16 A.M. (Eastern Daylight Time) at Kennedy, but continued inclement weather in Florida could shift the site to Edwards Air Force Base in California, which has two landing opportunities Saturday. Landing in California is not as desirable because the shuttle must then be ferried back to Kennedy atop a specially equipped NASA 747 at a reported cost of $1.8 million. Such was the case after space shuttle Endeavour landed at Edwards at the end of November—click here to see an overhead photograph of the orbiter hitching a ride back to the East Coast.

Temperatures on the Eastern seaboard have risen to the high 80s and low 90s in recent days, 20 to 30 degrees Fahrenheit above normal for April in the region. Here in New York City, where Scientific American's offices are located, we may break the record high of 90 degrees Fahrenheit on this date set back in 1990. But as the temperature climbs in the Northeast and summer wilt sets in before trees have even budded out, it's worth remembering that weather is not climate.

Weather is the day-to-day temperature, humidity or precipitation that determines whether you'll wear your spring coat or strip down for summer. Climate is the overall combination of all these elements over a long period of time.

Temperature records kept since the 19th century reveal that global average temperatures are inexorably creeping up, a phenomenon dubbed climate change. The cause? Increasing levels of greenhouse gases, most commonly carbon dioxide, in the atmosphere, which trap heat that would otherwise radiate back out to space, like a smothering blanket.

In one of the oddities of parsing the regional effects of global climate change, researchers have noted that the U.S. Southeast has seen average high temperatures dip by as much as 0.38 degrees Fahrenheit (0.21 degrees Celsius) over the course of the 20th century. Curious, atmospheric scientist Robert Portmann of the National Oceanic and Atmospheric Administration (NOAA) and his colleagues decided to take a look at what might be causing it.

Their findings, published yesterday in the Proceedings of the National Academy of Sciences USA: that increasing spring rainfall during May and June each year in parts of the southeastern U.S. appeared to be keeping down average high temperatures, based on a study of thousands of readings from weather stations in the Global Historical Climatology Network Daily system.

Suffer from headaches?  It could be the weather, according to a new study.

"There are a lot of potential triggers of headache. …[weather] is something for clinicians to consider in evaluating what each person's triggers are," says Kenneth Mukumal, an internist at Beth Israel Deaconess Medical Center in Boston and lead author of the research published  this week in Neurology.

Mukamal and his colleagues studied more than 7,000 Boston-area patients diagnosed with headaches at the Beth Israel Deaconess Medical Center emergency room between May 2000 and December 2007. To determine if weather played a role, they scoured National Weather Service data on fluctuations in temperature, humidity, and barometric pressure that occurred within 72 hours of each patient's ER visit.

Tropical Storm Hanna may not be a hurricane, but it's still dumping tons of water on the US east coast as it moves northeast this afternoon. US officials have not reported any deaths from the storm, which is bearing down on New Jersey and will likely travel over Boston very early tomorrow morning, according to the National Hurricane Center.

Some 60,000 homes lost power in North Carolina earlier in the day, although more than a third of those had power back, Reuters is reporting. The storm has left as much as five inches of rain in some locations.

Meanwhile, all eyes are on Hurricane Ike, which as of 5 p.m. EST Saturday was packing winds of 135 mph, making it an extremely dangerous Category 4 hurricane. Earlier, AccuWeather was predicting that Ike's strength will ebb and flow between Category 2 and 3 as it makes its way west through the Caribbean, hitting Cuba Monday morning as a Category 2. It will likely gather strength as it leaves Cuba for open Gulf of Mexico waters on Wednesday morning, which means it could threaten the Florida Keys. Officials there began evacuating residents this morning.