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As it happened: Malaysian Grand Prix Weather
By Emlyn Hughes
The live commentary has ended. No further updates will be posted.
Mon 15:00 Formula 1 delivered one of its best races in a long time yesterday in Australia, but the teams and drivers have had precious little time to look back on a spectacular event.

They are already bound for Kuala Lumpur International Airport to begin unpacking and preparing for the next race. Intense heat and energy-sapping humidity awaits the 12 teams, as they gear up for the Malaysian Grand Prix from the Sepang F1 Circuit.

By now we all know the standard weather form at Sepang - it's like groundhog day. Temperatures hit around 32 degrees in the heat of the afternoon, cooling to 24 or 25 Celsius by night.

The heat isn't so much of a problem - after all, the sport travels to hot destinations several times during the season. It's the high humidity of up to 75 or 80 percent - even on a day when no storms occur - that drains away the energy levels and can have you dripping with sweat in a matter of minutes, just from walking around.

Of course, the Formula 1 fraternity will experience more of the same this weekend, but the important aspect of the weather at Sepang is always the thunderstorm potential.

Early Forecast

Current weather forecast models indicate that Friday is likely to stay dry, given the scheduled time for the two practice sessions. Throughout March it has only rained three times during the window that the cars will be on the circuit, so a dry Friday is highly likely with a maximum air temperature of 31 Celsius.

Saturday and Sunday sees the programme of track running move to late afternoon for the benefit of European television viewers. Early predictions suggest that there is a high chance of a storm on Saturday with air temperature on the low side, reaching only 30 degrees.

History has taught us that there are two types of rainfall at Sepang - the intense rainfall delivered by thunderstorms such as in 2001 and 2009 during the race, or the short spells of light rain and sprinkles - such as we saw during the early laps of the 2004 event.

The forecast for Sunday suggests that we may see the latter during late afternoon or early evening, but nothing - yet - indicates there will be storms. It will be warmer than either Friday or Saturday with a maximum of 33 degrees.

On Thursday AUTOSPORT Live will bring you up to date with all the weather news from the circuit, detailing any storms that occur between now and then, and of course we will have the latest forecast for the weekend.

Jenson Button and his McLaren engineers run for cover as a downpour strikes Sepang
Jenson Button and his McLaren engineers run for cover from a downpour at Sepang © Sutton
Thu 11:00 The Sepang F1 Circuit was a hive of activity today as the drivers and team members consigned Melbourne to history and looked ahead to this weekend's Malaysian Grand Prix.

Precision driving and getting the right line were top of the agenda this afternoon - but only for the track road sweepers as they toured the 5.543 km track in a bid to ensure that the surface is as clean as possible for tomorrow's free practice sessions.

Thunderstorm Activity

The mere sight of road sweepers clearing dust off the racing line would logically suggest that Sepang has remained dry all week, but that certainly isn't the case. Monday's storm lasted almost three hours before clearing away at eight o'clock in the evening. Then, on Tuesday, a much shorter period of storm activity occurred at five o'clock with light sprinkles to end the day.

Wednesday produced light sprinkles in the morning, followed by a 3pm storm - only the fourth such storm in March that falls within the Friday practice time frame. Light rain fell later at night.

Today has been dry and very hot with a maximum temperature of 35 degrees. Shortly after 5pm, the daily detonation hit the circuit from the north-east, giving the track another thorough soaking with a typical hefty downpour.

Weekend Forecast

The potential for severe storms is forecast to reduce - slightly - as we head into the event and Friday should tee us off nicely by just escaping any wet weather. There is a chance of some light rain early in the morning, but this will have cleared by the time first practice begins. Dry and increasingly warm conditions will be the order of the day, with temperatures reaching 32 degrees under increasingly cloudy skies.

Saturday's final practice session is expected to take place in dry and hot conditions, but the forecast for qualifying is a little more uncertain because it ends at 5pm local time. Thundery showers could heighten the drama towards the end of the session as temperatures again top 30 Celsius.

Race day is then set to dawn dry, hot and mainly sunny. But, as usual, the clouds will develop in the afternoon. The second half of the race, after 5pm, is certainly when the daily risk of thundery rain will be at its greatest. Temperatures will once again reach 32 degrees Celsius.

Who will set the early pace at Sepang? Join us for full coverage of Friday practice, starting with the morning session from 01:45 GMT.

Clouds build above Sepang
Clouds build above Sepang © Sutton
Fri 11:05 A stray shower during the break between sessions did little to affect the running of two dry sessions of practice for Sunday's Malaysian Grand Prix. But, shortly after the end of practice two, the heavens opened again, giving the circuit a thorough soaking.

Today's big storm thankfully lost its severe intensity as it approached the circuit this evening, but nevertheless enough rain fell in a short space of time to make track conditions treacherous.

Latest weather models point towards an increasing chance of afternoon storms on Saturday.

Groundhog day will begin as usual with hazy sunshine and a few clouds around, but the progression to cloudy and then overcast conditions is expected to occur sooner than it did today. The risk of heavy showers will already be high by the time final practice begins - and that storm risk only increases as we move through to qualifying.

The maximum temperature will reach 30 degrees Celsius, but this may not be a factor given the higher chance of storm cells forming.

Race day also has the potential for storms, but latest model calculations suggest the risk is slightly less than on Saturday. The day will start dry with some sunshine around, but into the afternoon cloud cover will build, with the main storm risk occurring from around 16:00 local time - the start time for the race.

Given the weather models predict increasing convective potential energy, and therefore risk of thundery showers, we rate the chance of rain affecting Saturday running at 80 percent, dropping slightly to 70 percent for Sunday.

AUTOSPORT Live will begin coverage of the final practice session from Sepang tomorrow at 04:45 GMT.

Mark Webber grabbed pole for Red Bull as the rain hit Sepang during qualifying
Mark Webber grabbed pole for Red Bull as the rain hit Sepang during qualifying © LAT
Sat 10:47 While others lost in the casino that was Malaysian Grand Prix qualifying, Mark Webber gambled on intermediate tyres to grab a sensational pole for tomorrow's 56-lap race.

The showers were threatening even in final practice, but it soon became clear that rain would make an appearance in qualifying to spice up the grid. A further band of rain is due to hit the circuit this evening, before finally clearing away to end a very interesting day.

Tomorrow will dawn dry and mostly clear, but as usual here at Sepang it won't take long before the cloud begins to build from the east. The convective potential in the atmosphere tomorrow is now expected to be slightly higher than we saw today - making for another stormy forecast.

The rain threat will kick in from around 13:00, with the race starting at 16:00 local time. Rain is highly likely to feature once again, but the devil will be in the detail tomorrow afternoon. How quickly the showers develop and how close to the circuit will be the key and all eyes will be on the radar screens.

We do expect rain to fall during the planned two-hour window of the grand prix, meaning that like qualifying, the race could become a lottery, with the air temperature reaching 32 degrees Celsius prior to the start.

Can Mark Webber keep it together this time and win from the front row of the grid? Join us from 06:30 GMT for all the build-up to the Malaysian Grand Prix.

Monday 29 Mar Start GMT
 Malaysian Grand Prix Weather 15:00
Friday 02 Apr
 Friday Morning Practice 01:45
 Friday Afternoon Practice 05:45
Saturday 03 Apr
 Saturday Practice 04:45
 Qualifying 07:45
Sunday 04 Apr
 Race day at Sepang 06:30