A much-anticipated total solar eclipse will cross a large stretch of the United States on Monday afternoon but cloudy weather could spoil the view for millions of Americans.

The path of totality — when the moon fully blocks the sun — will occur along a 100-mile-wide stretch from Texas to Maine, giving people in Dallas, Indianapolis, Cleveland and Buffalo, N.Y., prime seats. It will be the last total eclipse over the United States for 20 years.

Solar Eclipse Time

The moon will block the sun for up to 4 minutes, and 28 seconds but the sun will be partially covered for a much longer period.

The partial eclipse starts at 12:23 p.m. CDT in Dallas with the total eclipse beginning at 1:40 p.m. In Clevland, the partial eclipse starts at 1:59 p.m. with the total solar eclipse starting at 3:13 p.m. EDT. And in Caribou, Maine the event starts at 2:22 p.m. EDT and the full eclipse starts at 3:32 p.m. with the peak at 3:33 p.m. EDT, according to NASA.

NASA has a tool on its website that shows what areas of the country will be impacted and the times of the total eclipse.

Solar Eclipse Weather

The National Weather Service says northern New England remains the best location for clear viewing of the total solar eclipse on Monday afternoon.

Southern Texas will likely have fair conditions in the morning but will likely followed by a rapid untimely increase of clouds into the afternoon, prior to the arrival of the solar eclipse. In contrast, northern New England remains the region where cloud cover will likely be minimized along the path of totality, as a swirling nor'easter moves farther out into the Atlantic. It appears that other locations in between will have a fair chance of cloud cover at various levels, although locations across Arkansas to the Midwest could see breaks in the clouds or high thin clouds during the time of totality.

How to Watch Eclipse Online

If you are in an area that will have bad weather or are not going to be in the path of the eclipse, you will have plenty of opportunities to watch it online. NASA will start coverage at 1 p.m. EDT. Its coverage will include conversations with experts and provide telescope views of the eclipse from several sites along the eclipse path.

Throughout the broadcast, they will answer viewer questions in the chat.

Solar Eclipse Glasses

Except for a specific and brief period of time during a total solar eclipse, you must never look directly at the sun without proper eye protection, such as safe solar viewing glasses, or eclipse glasses. Eclipse glasses are not the same as regular sunglasses. Regular sunglasses are not safe for viewing the sun, NASA warns.

If you are in an area that will experience the total eclipse, you can take your glasses off during the short time when the moon completely obscures the sun, known as the period of totality.

How to View Eclipse Without Glasses

If you don't have eclipse glasses, you can use an indirect viewing method, such as a pinhole projector, which projects an image of the sun onto a nearby surface. Here are instructions on how to build one with items you may already have in your home.