The setting sun aligns with Melbourne's CBD grid tonight, in what is being dubbed "Melbourne Henge".

A similar phenomenon in New York City is known as "Manhattan Henge".

Swinburne University astronomer Alan Duffy said the sun would set shortly before 8:00pm (AEDT) tonight at an angle of 250 degrees west.

"We're going to get this beautiful alignment of the setting sun and the Hoddle Grid," he told 774 ABC Melbourne's Jon Faine.

Melbourne's CBD grid is known as the Hoddle Grid because it was designed in 1837 by surveyor Robert Hoddle.

"Weather permitting ... the light will completely shine between the sky scrapers as if they were 400-metre-high stone henges," Dr Duffy said.

"It will be this beautiful sunset streaking up the entire mile-length of the Hoddle Grid."

Are you going to photograph Melbourne Henge? Tag us on instagram at @774ABCMelbourne, use the hashtag #MelbHenge on Twitter, or post the photo on our Facebook page.

Dr Duffy said he thought the best view would be from Williams St looking west down Collins Street or Flinders Lane, but predicting exactly where to watch was "a challenge".

"I'm excited to get some feedback from people," he said.

BOM says cloud may spoil view

Dr Duffy said after tonight the next Melbourne Henge sunset was due to occur on February 7, 2016.

"We can really get prepared for this second chance when we get the feedback from this first go about at exactly what street we get the best alignment," Dr Duffy said.

Dr Alan Duffy says the next "Melbourne Henge" sunset will be on February 7, 2016. ( The Drum )

However, Bureau of Meteorology (BOM) senior forecaster Dean Stewart said the weather was likely to get in the way this evening.

"Unfortunately I think where will be a lot of cloud out to our west tonight," he said.

"There's a very slight chance right at its setting it might sneak under that high level cloud, but I'd say the odds were against us at the moment."

Dr Duffy said there was a chance people could still view the phenomenon tomorrow evening.

"You might still get lucky tomorrow — the sun is only one degree further along the horizon," Dr Duffy said.

"That's about a thumb's width at your arm's stretched full out ... so you still might be able to get this canyon effect going even tomorrow night too."