July was the hottest month on Earth since records began, averaging 16.6 C (61.9 F), according to US scientists.
That is 0.08 degrees higher than the previous record, set in July 1998 - a significant margin in weather records.
Scientists at the US National Oceanic and Atmospheric Administration (NOAA) said in a report that they expect 2015 to be the hottest year on record.
Nine of the 10 hottest months since records began in 1880 have occurred since 2005, they NOAA report said.
Scientists say global climate change and the impacts of the El Nino weather phenomenon are behind the record temperatures.
The first seven months of 2015 have already set an all-time temperature record for the period.
"The world is warming. It is continuing to warm. That is being shown time and time again in our data," said Jake Crouch, physical scientist at NOAA's National Centres for Environmental Information.
"Now that we are fairly certain that 2015 will be the warmest year on record, it is time to start looking at what are the impacts of that? What does that mean for people on the ground?" Mr Crouch said.
Analysis: Matt McGrath, BBC Environment Correspondent
That July was an extremely hot month shouldn't come as a huge surprise. It's normally the warmest month of the year for the world as a whole.
According to the Met Office, the UK had its warmest July day ever on July 1, when temperatures hit 36.7 C near London. There were record heat waves in many countries including Spain, while the African continent had the second-warmest July on record.
While the impact of increased levels of carbon dioxide in the atmosphere is a key driver of rising temperatures, another important factor is El Nino. This natural phenomenon, which appears as a large swathe of warm water in the Pacific every few years, is known to push up global temperatures.
In recent days there have been reports that this year's El Nino will be particularly intense. As a result, many experts believe that 2015 will be the warmest year on record by some margin.
The seas have also been soaking up a large amount of heat, the NOAA said, with record warming in large expanses of the Pacific and Indian Oceans.
When scientists looked at both sea and land for the year to date, they found combined a combined average temperature of 0.85 C above the 20th-Century average.
The NOAA calculated the rate of temperature increase for July at an average of 0.65 C per century.
Peter Stott, head of climate monitoring and attribution at the UK Met Office, said: "A strong El Nino is under way in the tropical Pacific and this, combined with the long-term global warming trend, means there is the potential to see some very warm months throughout this year - as the new figures for July appear to show.
"This is consistent with the Met Office's global temperature forecast which predicted that a record or near record year is very much on the cards for 2015."
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