The phrase "are being warned of" is correct and usable in written English.
It can be used when indicating that someone is currently receiving a warning about something.
Example: "Residents are being warned of severe weather conditions expected this weekend."
Alternatives: "are being alerted to" or "are being cautioned about".
Now, the Irish are being warned of more pain to come.
Motorists, pedestrians and cyclists are being warned of the risk of frost and ice on roads.
Communities across southern England are being warned of the risk of further flooding from rivers swollen by recent heavy rain.
Elsewhere, heavy rain is likely to make tomorrow a washout for many and those heading for the hills are being warned of snow showers.
Holidaymakers trying to use the Channel Tunnel are being warned of hours of delays today after "intense migrant activity" disrupted trains from France.
Once again, we are being warned of a terrorist threat greater than any of the previous "threats greater than", this time from Isis.
The south coast of England will be among the hottest parts of the UK on Friday but anyone taking a dip in the sea is being warned of unwelcome visitors.
Southampton Airport said extra flights were being laid on following Monday's disruption but passengers were being warned of delays and urged to allow extra time for their journeys.
The disheartening truth is that ENTs were being warned of the risk but chose to dismiss the suffering of victims, some even ridiculing their suffocating patients as having "empty head syndrome".
Students are being warned to beware of scams involving privately rented property, following research by Shelter showing that up to 1 million people could have fallen victim to "landlord scams" in the past three years.
Computer users are being warned to be wary of email messages which suggest they contain nude photographs of girlfriends, or claim that they have been reported to the police, as the attached file (Photo.zip) really contains a Trojan horse.
