When President Bush warns that "time is not on our side" in halting Iraq's weapons threat, his sense of urgency may also reflect US military timing priorities.
November through February is the optimal window for an Iraq campaign, given seasonal considerations of daylight, temperature, and climate, military experts say.
Clearly, other major factors would loom large in a decision on when to strike Iraq from whether Washington can secure crucial bases and overflight rights to international and domestic politics.
Yet from a military tactical perspective, weather can play a decisive role on selecting the timing of a US invasion of Iraqi soil.
While the US military can operate in all weather conditions, it is no accident that US commanders chose to launch the first airstrikes of the 1991 Gulf War in the middle of January.
One prime consideration for US ground troops is to avoid the hotter months of Iraq's desert climate similar to that of the Southwestern United States with temperatures averaging over 100 degrees F. in summer.
Given the potential risk of Iraqi chemical and biological weapons, troops must be prepared to wear heavy protective suits, which can limit activity and cause overheating.
"In the summer there's not a lot you can do in a MOPP [Mission Oriented Protective Posture] suit," says James Carafano, senior fellow at the Center for Strategic and Budgetary Assessments here.
The military's current suit, a 1997 model that contains activated charcoal to protect against exposure to deadly agents, is relatively heavy (5.6 pounds for a medium size), bulky, and hot.
"As you button the system, you are not allowing air circulation, and the body temperature does rise," says Sarah Clybourne, an expert on the gear at Fort Belvoir in Virginia.
New, lighter suits using plastic membrane are undergoing extensive testing but won't be ready for "a year or two," says Eugene Wilusz, leader of the chemical technology team at the Soldier Systems Center in Natick, Mass.
In the months spanning winter, the shorter stretches of daylight would also extend the advantage the US military has operating in darkness, say experts.
Powerful night-vision capabilities allow the US military to move and strike targets while unseen by the enemy, gaining an element of surprise that has proven critical in military operations such as in Afghanistan.
"The shorter the days get, the more night, and US forces rule the night," says retired Navy Rear Adm. Stephen Baker of the Center for Defense Information.
"With our infrared capability, heat sources are much more identifiable [in darkness]," he says.
Other winter weather factors can have mixed implications for military operations, but do not pose serious obstacles, military experts and meteorologists say.
Winter marks the rainy season in Iraq, with 90 percent of the annual rainfall occurring between November and April, the majority of it between December and March.
As a result, cloud cover exists for about half the days in winter and can complicate the use of laser-guided missiles and other weapons.
However, the cloud cover is less of a problem in Iraq than in other theaters, such as Kosovo, experts say. Also, compared with the Gulf War, the US military currently uses a far higher percentage of GPS (Global Positioning System)-guided bombs, which are not limited by cloud cover.
"Cloud cover is a negligible factor [in Iraq]," says Colonel Carafano. "We have a lot more GPS capability, so we are better off in terms of our ability to attack in all weather."
Rains can also cause flash flooding in dry stream beds and roads in Iraq during the cool season, especially in early spring, although experts say the US military could maneuver around such areas without difficulty.
Finally, sudden dust and sandstorms can blow through year-round in Iraq, with the potential to ground planes or make flying hazardous.
Nevertheless, military meteorologists point out that such storms, while hindering air operations, might help cloak a ground action.
"If you are trying to attack with ground forces, it is always better to have some weather" to prevent detection by the enemy, says Major David Wood, chief of the special operations support branch of the Air Force Weather Agency at Offutt Air Force Base in Omaha, Neb.
Indeed, Air Force meteorologists say they study a host of complex factors from solar flares to wind and tide directions to assist military planners in making decisions.
"Our role is to provide information so the military planners can best employ the US instruments of national power," says Col. Bill Burnette, vice commander of the Air Force Weather Agency.
At the same time, compared with before the 1991 war, US military commanders and troops have far more experience fighting in a desert environment. The same goes for soldiers.
"Before 1990, you could not find many troops who had been to the desert," Carafano says. "Now, lots of people have been in the theater, and they have a lot more operational experience running things in all kinds of weather. The confidence level is way higher."