Millions of people across North America readied for a total solar eclipse on Monday — some gazing anxiously at wayward clouds — as the moon began creeping across the face of the sun in western Mexico before it blocks it out completely. However, the celestial event will not be visible in Pakistan or India.

According to the Pakistan Meteorological Department (PMD), the eclipse will be visible from the west in “Europe, North America [and] north in South America, Pacific, Atlantic and Arctic”.

“However it will be not visible in Pakistan,” it added.

Meanwhile, Hindustan Times reported that the total solar eclipse would also not be visible in India.

The total eclipse will be viewable along a path starting in western Mexico and then crossing through the United States and into Canada and will last more than four minutes in some places.

That is where Michael Zeiler, a veteran eclipse chaser from New Mexico who already has witnessed 11 total eclipses across the globe, plans to be.

“First-time viewers of a total eclipse will be gobsmacked by the sight,” Zeiler said. “It will be a peak life experience.”

Forecasters have said the weather could be cloudy in a large portion of the path of totality.

Zeiler, a cartographer and amateur astronomer, said he would study satellite images in the hours before the eclipse and would hustle if needed in his car at the last moment to a spot where clear skies are expected. Zeiler created the Great American Eclipse website, filled with maps and data on eclipses.

The Mexican beachside resort town of Mazatlan was the first major viewing spot in North America. Thousands of people gathered along the coastal promenade, setting themselves up in deck chairs with eclipse glasses as an orchestra played the “Star Wars” theme.

Lourdes Corro, 43, travelled 10 hours by car to get there.

“The last one I saw was when I was 9 years old,” Corro said. “There are a few clouds but we can still see the sun.”

Eclipse fans are gathering in numerous places along the “path of totality”.

In upstate New York, for instance, the total eclipse will occur shortly after 3pm (1900 GMT). At the Frontier Town campground in North Hudson, New York, children ran around wearing eclipse T-shirts, while parents set up tables, chairs and beer coolers.

Connecticut residents Bob and Teresa Love were stretched out in the cargo bed of their pickup truck, eating pastries and hoping the forecasted clouds hold off long enough to not obscure the spectacle.

“I’m trying not to get too excited because of weather, just trying to keep expectations real,” said Teresa, 49. “Some people say it’s life-changing. I don’t know if it’s going to be life-changing, but I think it’s going to be cool to see.”

At up to four minutes and 28 seconds, this one will last longer than the total eclipse that streaked across parts of the United States in 2017, which clocked in at up to two minutes and 42 seconds. According to Nasa, total eclipses can last anywhere from 10 seconds to about 7-1/2 minutes.

Some other cities along the path of totality include San Antonio, Austin and Dallas, Texas; Indianapolis, Indiana; Cleveland, Ohio; Erie, Pennsylvania; both Niagara Falls, New York, and Niagara Falls, Ontario, site of the famed waterfall, and Montreal, Quebec.

A partial eclipse will be visible in North America outside the path of totality.

About 32 million people in the United States live within the path of totality, with federal officials predicting another 5m people will travel to be there. Countless eclipse-watching events were being convened at bars, stadiums, fairgrounds and parks along the path of totality.

Small rural towns bustled, such as Advance, Missouri, home to just over 1,300 people, where Tim and Gwen Wurst had driven from their Kansas City home after checking weather forecasts. They were thrilled to witness a partial eclipse in 2017 and were excited for the totality.

“It’s been on the calendar for years,” said Tim Wurst, 62. “It was very dusky and dim the last eclipse, but this one should be just all-out dark.”

Experts have urged the use of protective solar glasses to prevent eye damage from looking at the sun with the naked eye. Only during the few minutes of totality can the sun be safely viewed without such glasses, they said.

Overcast skies are among an eclipse-chaser’s worst fears.

The US National Weather Services forecast as of Monday morning was for “a rapid untimely increase of clouds” in Southern Texas; less worrying “high thin clouds” for a swathe from Arkansas to the Midwest; and the clearest skies in northern New England.

It will take about 80 minutes from the moment the moon first begins to cover the sun to the moment of totality, then another 80 minutes to complete the process in reverse.

Eclipse veterans have described the 15 minutes before totality as foreboding, with shadows becoming oddly crisp and sunshine assuming an eerie quality.

In the seconds before totality, a phenomenon called “shadow bands” may appear as shimmering shadows on the ground, like those seen on the bottom of a swimming pool.

The last remaining bit of brilliant sunlight before totality creates a “diamond ring effect” in which a single bright spot appears along the lunar edge even as the sun’s atmosphere leaves a ring of light around the moon.

This will be the ninth total eclipse for Anthony Aveni, author of the book “In the Shadow of the Moon: The Science, Magic and Mystery of Solar Eclipses,” and each one has inspired deep awe in everyone around him who saw it. He said people frequently burst into tears and hug complete strangers.

“No matter who you are or when you lived, the sight of an eclipse begins with fear,” Aveni said. “The imagery shocks you. That fear is gradually transformed into awe and then into a sublime state.”