“This is an S4 severe solar radiation storm and the largest we’ve seen in over 20 years,” the SWPC said in an update on X(Formerly known as twitter. “The last time storms of this level occurred was in October 2003, and the main effects are expected to impact space launches, aviation and satellite operations.”

Solar storms of that magnitude have caused serious problems in the past. The well-known Halloween storms of 2003 led to power outages in parts of Sweden and damage to power equipment in South Africa, the agency noted.

When this kind of radiation reaches Earth, it increases exposure risks for astronauts aboard the International Space Station and for passengers flying on routes that pass over the poles. Because of this, the SWPC has already alerted several key organisations, including airlines, NASA and emergency management authorities, to prepare for potential impacts.

Astronauts can limit their exposure during such events by moving to better-shielded sections of the space station, a step taken during past storms, including a major geomagnetic event in May last year. Elevated radiation levels can also affect satellites that support communication, navigation and GPS services.

Ryan French, a solar physicist at the University of Colorado Boulder, said satellite operators may need to take precautionary steps overnight, but major problems for everyday users are unlikely. The general public should not expect widespread technology failures, he said.

Alongside the radiation storm, a strong geomagnetic storm reached Earth on Monday afternoon, which can sometimes interfere with power grids. These storms are caused by huge bursts of plasma and magnetic fields from the Sun, known as coronal mass ejections, that disturb Earth’s magnetic field when they strike.

The latest eruption was triggered by an X-class solar flare, the most powerful type, marking the first major flare of the year. Such activity is also responsible for creating auroras near Earth’s poles.

When charged particles collide with gases high in the atmosphere, they produce glowing waves of colour known as the northern and southern lights. This time, those displays could stretch much farther south than usual. The SWPC said auroras may be visible across much of the northern United States and possibly as far south as Alabama and northern California. And no signs of it being visible in India.

Those bursts, known as substorms, typically last around 20 minutes and can dramatically intensify the display. Scientists also warn that the active sunspot region responsible for this storm may produce more flares in the coming days, raising the possibility of additional solar eruptions aimed toward Earth.