Donald Trump's blockbuster UFC fight night at the White House is facing an unexpected threat before a single punch is thrown: swarms of insects.

Experts are warning that Sunday's heavily promoted UFC Freedom 250 event could be hit by an 'extreme' bug invasion as soaring temperatures, humidity and the threat of thunderstorms create ideal conditions for mosquitoes, gnats and other pests to descend on the South Lawn.

The warning comes as workers put the finishing touches on a sprawling outdoor arena erected outside the White House for what is shaping up to be one of the most extraordinary sporting events ever staged at the presidential residence.

Forecasts show temperatures climbing to around 91F in Washington, DC, on Sunday, with thunderstorms possible later in the day. 

But while rain and lightning could disrupt proceedings, insect experts say the city's notorious summer bug population may pose an equally troublesome challenge.

AccuWeather has issued an 'extreme' bug warning for the day of the event, citing weather conditions that encourage heightened insect activity and larger numbers of mosquitoes, stink bugs, roaches and termites.

The prospect of thousands of insects being drawn toward the powerful floodlights surrounding the Octagon is likely to concern UFC president Dana White, who has repeatedly expressed his dislike of outdoor fight cards because of the elements that organizers cannot control.

White recently recalled being stunned by the volume of insects he encountered while attending an event at the White House earlier this year.

'He invited me to dinner there,' White said of Trump during an interview with Boardroom Talks. 'The amount of gnats that are flying around, I'm like, 'Holy s***!'' 

The UFC boss nevertheless agreed to move forward with the event, a reflection of his long-standing friendship with Trump. 

Organizers have prepared a series of backup plans to deal with weather-related disruptions, including measures aimed at limiting the impact of heat, rain, wind and insects.

Industrial fans, protective coverings and other production adjustments are among the tools available should conditions deteriorate.

The festivities surrounding the event have already transformed several iconic Washington landmarks into staging grounds for what may become one of the most unusual combinations of politics and professional sports ever seen in the nation's capital.

Activities began Friday with a UFC press conference at the Lincoln Memorial, the historic site where Dr. Martin Luther King Jr. delivered his 'I Have a Dream' speech in 1963.

Saturday's ceremonial weigh-ins are scheduled for the Ellipse, the park adjacent to the White House that became internationally known after Trump's January 6, 2021 'Stop the Steal' rally.

The main attraction arrives Sunday night, when fighters including Ilia Topuria, Justin Gaethje, Alex Pereira and Ciryl Gane are expected to compete inside an Octagon erected beneath a towering steel lighting structure known in production circles as 'The Claw.'

Trump, who turns 80 this weekend, is expected to attend as thousands gather on the South Lawn for the event.

The president also announced Friday that the Department of War plans to unveil a new recruitment advertisement during the broadcast.

'This Sunday Night, during the historic Freedom 250 UFC Fight at the White House, The Department of War will debut their first TV Ad, entitled 'Peace Through Strength',' Trump wrote on Truth Social.

'The Warrior Ethos is BACK at the War Department, and we call on our greatest young Americans to join our Great Fighting (when necessary!)'

The event has generated controversy beyond concerns about insects and weather.

A lawsuit filed by two Washington-area residents alongside watchdog organization Public Integrity Project sought to stop the fights from taking place on federal property. The plaintiffs argued that government facilities were being used to benefit private commercial interests connected to both Trump and White.

Court documents described the event as an 'orgy of corruption.'

A judge ultimately declined to halt the proceedings, ruling Friday that the plaintiffs had failed to demonstrate sufficient harm to justify blocking the event.