The world is in the middle of what is likely to be the warmest 10 years since records began in 1850, says the Met Office.
It's forecasting that temperatures for each of the next five years are likely to be at or above 1C compared to pre-industrial levels.
There's also a small chance that one of the next five years will see global temperatures temporarily go above 1.5C.
That's seen as a critical threshold for climate change.
If the data matches the forecast, then the decade from 2014-2023 will be the warmest in more than 150 years of record keeping.
The Met Office says that 2015 was the first year in which the global annual average surface temperature reached 1C above the pre-industrial level, which is generally taken to mean the temperatures between 1850 and 1900.
We've just made this year's forecasts and they go out to 2023 and what they suggest is rapid warming globally," Prof Adam Scaife, head of long term forecasting at the Met Office, told BBC News.
"By looking at individual years in that forecast we can now see for the first time, there is a risk of a temporary, and I repeat temporary, exceedance of the all-important 1.5C threshold level set out in the Paris climate agreement."
Last October, UN scientists published a special report on the long-term impacts of a temperature rise of 1.5C.
They concluded that it would take a massive carbon cutting effort to keep the world from tipping over the limit by 2030. The Met Office analysis now says there's a 10% chance of this happening within the next five years.
"It's the first time the forecasts have shown a significant risk of exceedance - it is only temporary. We are talking about individual years fluctuating above the 1.5 degree level," said Prof Scaife.
"But the fact that that can happen now due to a combination of general warming and the fluctuations due to things like El Niño events in the next few years does mean we are getting close to that threshold."
The Met Office says it has a 90% confidence limit in the forecasts for the years ahead.
It says that from 2019 to 2023, we will see temperatures ranging from 1.03C to 1,57C above the 1850-1900 level, with enhanced warming over much of the globe, especially over areas like the Arctic.
The research team says it is pretty certain in its predictions because of its past experience. The team's previous forecast, made in 2013, predicted the rapid rate of warming that's been observed over the past five years. It even predicted some of the lesser known details such as the patch of cooling seen in the North Atlantic and the cooler spots in the Southern Ocean.