Luckily during the war, a volcano (Laki, Iceland) threw Europe & much of the British empire (including India & Africa) into a multiyear drought, causing one of the coldest/longest winters in the USA.
About 3 months after the eruption formal negotiations to end the war began.
No eruption, possibly no USA but historical accounts I've seen rarely mention the role of mother nature.
"The system erupted violently over an eight-month period between June 1783 and February 1784 from the Laki fissure and the adjoining volcano Grímsvötn, pouring out an estimated 42 billion tons or 14 km3 (3.4 cu mi) of basalt lava and clouds of poisonous hydrofluoric acid and sulfur dioxide compounds that contaminated the soil, leading to the death of over 50% of Iceland's livestock population, and the destruction of the vast majority of all crops. This led to a famine which then killed approximately 25% of the island's human population.[4] The lava flows also destroyed 20 villages.
The Laki eruption and its aftermath caused a drop in global temperatures, as 120 million tons of sulfur dioxide was spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in North Africa and India."
It goes on, in relation to the UK...
"Inhaling sulfur dioxide gas causes victims to choke as their internal soft tissue swells – the gas reacts with the moisture in lungs and produces sulfurous acid.[20] The local death rate in Chartres was up by 5% during August and September, with more than 40 dead. In Great Britain, the east of England was most affected. The records show that the additional deaths were among outdoor workers; the death rate in Bedfordshire, Lincolnshire and the east coast was perhaps two or three times the normal rate. It has been estimated that 23,000 British people died from the poisoning.[21]"
And a burned down White House
In fact, it's the reason the capital of Canada is Ottawa today. When the Province of Canada was established, it was deemed that York (which is now Toronto) was way too vulnerable since a US army could get there from Buffalo in less than a day and ships from Rochester even faster. By contrast, Ottawa (then called Bytown) was surrounded by swamps, further inland, well away from any US city, but still had access to rivers so it wasn't excessively isolated.
That and the fact that it was halfway between Toronto/Kingston (the English cities) and Montreal/Quebec City (the French cities) also made it a good political compromise.
So without that war, Toronto would probably be the Canadian capital and Ottawa would be a glorified rest spot between Toronto and Montreal.