About 30 students were being assessed by paramedics at Clancy Catholic College in West Hoxton following the reported lightning strike at 9.40am on Tuesday.

A NSW Ambulance spokeswoman said up to 12 teenagers, mainly girls, were reporting symptoms of headaches and dizziness. A number of students were also believed to be feeling numbness in their limbs.

A triage command post had been set up at the college on Carmichael Drive to treat and assess the students. Two students were later taken to hospital for observation.

Initial callers to triple-0 said lightning had struck the oval where the students, aged between 13 and 14, were standing.

The NSW Ambulance spokeswoman said witnesses had reported that a large clap of thunder was heard at the time, but she said it was "hard to ascertain whether there had actually been a lightning strike", or whether it was some type of "static electricity discharge".

Weatherzone meteorologist Rob Sharpe said there had been a couple of lightning strikes in the West Hoxton region at the time the students fell ill.

"It's entirely plausible that lightning did strike [at the school]," he said.

Head of Communications at the Catholic Education Office, Mark Rix, said the group of year 7 students had been on the oval at about 9.15am as part of their practical PDHPE lesson when they heard a rumble of thunder then felt a "tingling" sensation like a "mild shock".

"A couple of students talked about feeling like their hair was standing up," he said.

None of the students saw lightning but they all felt the strange sensation, including the teacher who quickly ushered the class inside before an ambulance was called.

Two students were taken to hospital as a precaution and one remained there for observation, he said.

The school oval and an adjoining basketball court remain closed for the rest of the day.

The State Emergency Service said it had not responded to any calls for damage caused by lightning strikes or storms in the West Hoxton area on Tuesday morning.

Mr Sharpe said a wave of storms had been sweeping across mainly southern parts of Sydney, bringing brief bursts of heavy rain.

The thunderstorms were fast moving and were likely to peter out by 11.30am or so before some storms returned later in the day, Mr Sharpe said.

The gusty winds and warm temperatures "are a bit of a taster of the type of weather Sydney will see more of later in the spring", Mr Sharpe said.

The winds are also whipping up the pollen, raising the rating to high for Tuesday even with the showers and heavier falls for some parts of the city.

with Bellinda Kontominas

Weatherzone is owned by Fairfax Media, publisher of this website.