Following another rain-hit day of testing on Friday, Button thinks that he and team-mate Sergio Perez are still a little way off feeling totally comfortable with the new MP4-28.
"If we have two straightforward days then yes, I think it is enough time to be ready for Australia," Button told media in the Barcelona paddock.
"But if we have too much downtime or the weather is bad it will be tricky.
"I am sure we can deal with it and still do a good job in Australia. Personally I feel there is more development in terms of set-up, and there is so much more we can achieve over these two days so we need it to be good weather and reliable."
Button says a combination of bad weather and the excessive tyre degradation that has led to graining has made it difficult to fully understand the new McLaren.
Allied to that, he also admits that matters have not been helped by the team losing valuable running time through needing to make lengthy set-up changes.
"When we do a set-up change it does take a long time," he said. "That is normal with a new car but still it has taken a bit too long.
"That has cost us a bit of time in the garage and hurt our comparisons on circuit. That is something we need to improve.
"Dry weather for two days and circuit temps in the 20s/30s is what we need, since I haven't driven in those conditions since Jerez. All the other days I've driven have been freezing cold.
"It would be nice to drive in slightly hotter conditions that were comparable."
Button was eager to emphasise, however, that he was not unduly concerned about the situation.
When asked if he was worried by McLaren's state of readiness, he said: "That is not a word I would use. I am not worried, no. I am not alarmed, no.
"I am looking forward to doing the last day of testing but it is very much needed."
He added: "I like driving the car. It is a nice car to drive, and there is nothing that scares me about the car.
"But I still feel that we can do a lot more with it than we are at the moment. And that is the exciting part.
"There is still room for improvement and we are not at the end, not ready to go racing. I still feel we can do more with it."
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