Why is it so humid in Melbourne right now?

It wouldn't be out of the question to mistake Melbourne's weather over the past week for something tropical, as humidity levels reached "quite unusual" heights.

The Bureau of Meteorology's Morgan Pumpa told 9news.com.au that humidity levels have been significantly higher than usual.

The near-record humidity is expected to persist until at least Saturday afternoon.

Why is it so humid in Melbourne right now

The humidity is a result of an almost stationary trough lingering over the northern parts of the country, drawing tropical moisture into Victoria, according to the Bureau.

"We have been seeing some very high dew points in Victoria and South Australia from that system," Pumpa said.

Weather across Melbourne has been unpredictable today, with 24mm of rain already falling in the city.

Meanwhile, St Kilda recorded just 2.8mm of rain. 

"Today we again have quite that nature of shower and storm activity where it's going to be quite hit and miss with some of those showers," Pumpa said.

"(It's) a very active day."

"Once again with our thunderstorm activity, we've got all that humidity from that tropical moisture getting brought into the state."

Is Melbourne usually humid?

The Bureau said it was quite rare for Victoria to record high humidity levels for consecutive days.

"For November, it is quite unusual," Pumpa said.

"It does seem like the number of days where we've had humidity at 100 per cent, that is quite unusual for southeastern parts of Australia.

"But otherwise with that, we have seen quite a number of days where we've seen water vapor quite high."

The dew point temperature this morning peaked at 20.9 degrees, which is "very, very high".

Dew point refers to the temperature to which air must be cooled in order to produce condensation.

It represents how much moisture is in the air. The higher the dew point temperature, the greater the atmospheric moisture content, according to the Bureau.

By comparison, the dew point temperature in Darwin is currently 25 degrees.

"Even with that temperature being so high, that's really impacting people. Even though we're not in heatwave conditions, these are very humid conditions for November. We aren't even in summer just yet," Pumpa added.

Will the humidity ease in Melbourne and when will it get cooler?

Rainfall will ease tomorrow, but it will remain quite humid, with the possibility of thunderstorms in the morning and afternoon. The temperature will reach a high of 26 degrees.

Meanwhile, Friday will be slightly warmer, with a moderate chance of showers and thunderstorms, and a top temperature of 29 degrees.

Saturday is expected to be a bit cooler, with a high of 24 degrees. There is a high chance of showers, most likely in the afternoon and evening, along with the potential for thunderstorms.

The Bureau expects the humidity to ease by Sunday.

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