A suggested rise in the number of Welsh speakers over the last decade is "encouraging", the Welsh Government has said.
A survey by the Office of National Statistics (ONS) suggests 874,700 people are able to speak the language, up from 726,600 in 2008.
The Welsh Government wants to get one million people speaking Welsh by 2050.
Welsh Language minister Eluned Morgan said the results of the survey were very encouraging ahead of the census.
The data was published as part of the Annual Population Survey, which asked 31,000 people about their ability to speak Welsh in 14,500 different households in the different council areas across Wales.
While it suggests a rise in the number of Welsh speakers in most parts of Wales, the official data will not be known until the next census is carried out in 2021.
Traditional Welsh-speaking communities have been said to be under threat from young people moving away to find work and new housing developments attracting incomers who do not speak the language.
But according to the survey, by the end of June 2008, there were 726,600 people in Wales who said they could speak Welsh, or 25.8% of the population.
Now the sample suggests that 874,700, or 29.3% of the population, are able to speak the language.
According to the survey, the number of Welsh speakers for the population rose in every local authority apart from two, Flintshire, where numbers fell by about 6.2%, and Torfaen, where there was a 0.5% decrease.
Gwynedd remains the area with the highest percentage of Welsh speakers, making up 76.4% of the population.
While Pembrokeshire saw the largest increase in the number of people who claim they can speak the language, with almost 10% more of the population now able to speak it compared to in 2008.
Welsh Language minister Eluned Morgan said that while the information was "useful" the census would be the official source for its goal to reach its target of one million Welsh speakers over the next 30 years.
"These figures, however, are very encouraging, and I'm pleased to see that there has been an increase in the number of people who claim they can speak Welsh over the previous ten years"
The Welsh Language Commissioner Meri Huws told BBC Cymru Fyw: "The figures are encouraging and suggests we are moving in the right direction in our efforts of increasing the number of people who are Welsh speakers."
"It's also encouraging seeing the overall picture is pretty consistent throughout Wales."