Professor Kevin Fenton said anyone with swollen glands, a fever and blisters should stay at home during the celebrations to avoid spreading the virus.
He told BBC News: “If you think you may have monkeypox - blisters, fevers, swollen glands - please do not go out over the weekend.
“Stay at home and contact NHS 111 or your local sexual health service for advice.”
He said cases were likely to rise in the coming weeks due to a gap between infection and the emergence of symptoms.
There were 1,076 total UK monkeypox cases as of June 26, with 79 per cent of cases in London.
Health authorities have raced to contain the spread of the virus since it emerged in Britain on May 6 and suspected cases are expected to isolate for up to 21 days.
While most who contract the virus have a mild illness, with recovery within three weeks, some cases can cause severe illness and occasionally result in death.
Monkeypox is not a sexually transmitted infection but can be passed on by close contact.
Earlier this month, the UK Health Security Agency (UKHSA) announced gay and bisexual men at higher risk of being exposed to monkeypox would be offered the smallpox vaccine Imvanex.
The UKHSA said the jab had been shown to be effective against monkeypox.
Eligibility will depend on a number of factors but a clinician may advise vaccination for someone who has a “recent history of multiple partners, participating in group sex, attending sex on premises venues or a proxy marker such as recent bacterial STI in the past year”.
In other developments, scientists in South Korea on Wednesday announced a new PCR test for monkeypox that can deliver results in 90 minutes.
Diagnostics firm Seegene aims to roll out the test swiftly using its automated assay development system.
