By Doug Schneider

Rain showers will start to spread into the Le Mans area beginning tonight. Periods of showers are likely to continue through Saturday as a low pressure system sits over the Bay of Biscay. The most likely period for showers on Saturday will be in the afternoon and evening, during the opening hours of the race. There could be around a quarter of an inch (around 6 mm) of rain that falls on Saturday. 

Saturday night should have a lower chance of showers in the area. Coverage will be more scattered, and showers will be lighter. The threat of thunderstorms will also diminish. Scattered showers will continue around northern France through Sunday, and there may be some breaks in the clouds that allow some sun to briefly shine through. 

I will be travelling on vacation with family tomorrow, so I won't be able to post radar updates as I usually do. I recommend this site to monitor radar - https://www.meteo60.fr/radars-precipitations-pluie-france.php

By Doug Schneider

Not much has changed in the forecast for Le Mans with the latest data. Some things have come into better focus, such as the timing of the best chance of rain and potential rainfall amounts. 

High pressure over the British Isles will keep conditions dry and mild at Le Mans on Thursday, with mostly sunny skies. Clouds will start to increase a little on Friday as the high pressure system moves east and a low pressure system off the northwest coast of Spain approaches. As this low moves into the Bay of Biscay, it will start to bring a chance of rain into northern France, beginning Friday night. There is good agreement between the models that the center of the low will be just off the west coast of France on Saturday, sitting nearly stationary through the day. Shower and thunderstorms will be numerous across eastern and northern France all day, but the most likely time for showers to occur at the track will be in the late afternoon and evening - near the start time of the race. The rain could be briefly heavy if a storm moves directly over the track, with a quarter to a half inch of rain possible (6-12 mm). There could be a possibility of a caution period or a stoppage if the heavy rain and lightning occurs. 

The threat of showers will drop Saturday night, but it won't completely go away. There may be some scattered showers lingering around overnight and into Sunday morning. The chance of rain on Sunday looks lower than Saturday as the low pressure system is expected to weaken and drift southeast. Any showers on Sunday should be lighter as well, so the impact on the racing is expected to be less. 

By Doug Schneider

Warm temperatures and mostly sunny skies are expected at Le Mans through most of this week, but as we approach the weekend, the chance of rain still start to increase, and there's a good chance of seeing rain at some point during the race.

A large high pressure system will be drifting east from England to Scandinavia from Wednesday through Friday, providing dry weather and warm temperatures across northern France. A low pressure system will be tracking east across the Atlantic, and be located somewhere near the Bay of Biscay by the end of the week. This low pressure system will spread increasing moisture into France over the weekend. The chance of rain is a bit uncertain this far out, and it will depend on the exact position of this low, which isn't yet clear. If it tracks farther south as some models suggest, there will be a lower chance of rain. A more northerly position of the low will increase the rain chances. In this forecast, I have taken a middle ground, with rain chances in the 40-50% range. This may go up or down with later forecast updates, so check back through the week.

By Doug Schneider

Each year at Racecast Weather, we collect photos through the year of our two favorite things - weather and race cars - and pick the best to be featured in a final post to close out the year. Thanks to the extremely talented photographers (and not so talented, like myself) who took these photos - credit for each pops up when you hover over each image. Click on each image to view a larger size.

Thanks for following our forecasts through 2019, and Scott, Stephen, and I hope you have a very happy Christmas season. We'll see you again on December 30 with the forecast for the Roar Before the 24 in January.

By Doug Schneider

Click on images to enlarge

The start of the 24 Hours of Le Mans will be covered by clouds as an upper level trough and a surface cold front will be moving toward the area. Here's a look at the radar and satellite image at 1:30 pm:

Although the rain over Brittany is moving east and looks pretty solid now, it is expected to break up more as it approaches Le Mans. So I don't expect it to have much impact. If there is a shower this afternoon, it will be very light and short-lived. There may not even be enough to measure, maybe just a trace, which wouldn't even require a change to rain tires. 

Clouds will be decreasing in the evening, with partly cloudy skies by sunset. Temperatures overnight will fall into the upper 50s F or mid teens C. Mostly to partly cloudy skies can be expected from sunrise tomorrow through the end of the race, with no precipitation expected.

By Doug Schneider

​Click images to enlarge

The weather for Le Mans continues to progress as expected, and there hasn't been much change needed to the forecast today. The small chance of a shower on Saturday should not have an impact on the race.

There have been showers near the northern coast of France today, but they have stayed north of Le Mans. On Friday the weather pattern will feature a stationary low pressure system to the north of Ireland, and another moving from the western Mediterranean Sea to eastern France. The second low will bring rain to central and eastern France, but I expect that it will stay far enough away from Le Mans that I can keep the forecast dry. The weather for Friday's parade should be really nice, with mostly sunny skies and temperatures in the lower 70s F or lower 20s C. 

On Saturday the low pressure system to the north will bring a cold front and upper level trough across northern France. As it approaches Le Mans, it will be losing its punch and only a few isolated showers are expected in the area. If one of these showers does hit the track, it will likely be too light to have much impact, and they may arrive before the race begins. The most likely time for any showers is around noon, give or take a couple hours. Winds will be stronger on Saturday, blowing from the southwest at 10 to 15 mph or 16 to 24 km/h. 

High pressure will build over France on Sunday, providing nice weather for the finish and pleasant afternoon temperatures in the mid 70s F or lower 20s C. 

Sunrise at Le Mans is around 6 am, and sunset is around 10 pm. 

I'll have a more detailed forecast through the race posted on Saturday before the start.

By Doug Schneider

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Today will be a wet start to the 24 Hours of Le Mans activities, but the good news is that the forecast is looking better for drier weather on Thursday and Friday, while the weekend continues to look good for racing overall. 

Rain is spreading across northern France early this morning as a low pressure system is sitting over the region. It will move very little through today, so there will be periods of showers on and off all day long. Thunderstorms may be possible at times as well. I don't think the rain will be heavy enough to stop the practice and qualifying sessions, with a quarter to a half inch of rain expected (7 to 13 mm). However, if there is thunder in the area, then there could be some stoppages. That chance is fairly low, maybe 20 to 30%. 

The low will begin a northward drift on Wednesday night. As it does so, the chance of rain will begin to decrease. The system will be located over England on Thursday, so there could still be some showers across northern France that may affect Le Mans. I put the chance of that happening at 40%. If there is a shower on Thursday, I expect that it will be fairly light and brief, with little impact on the action.

Friday is looking better as the low is expected to be north of Ireland, with high pressure over the Alps building in. This should provide a dry day with warmer temperatures in the lower 70s F or lower 20s C.

On Saturday a trough rotating around the low pressure system to the northwest will pass across northern France. This could bring a few showers to the Le Mans area. The chance of one at the track is low, just 20%, and if it does happen it should be short-lived and light with little to no impact on the race. 

​I expect that Sunday will be dry, although there are some models that show some light showers popping up during the day. I'm not ready to go with that yet, so I'm keeping my forecast dry. Hopefully that holds up as we get closer to the weekend. 

By Doug Schneider

Click images to enlarge

The days leading up to the race weekend at Le Mans are likely to see a good amount of rain, but the good news is that the pattern is expected to change in time for the race.

A slow-moving low pressure system will be stalled over western France for the first half of the week. As I type this, showers and thunderstorms are occurring in the Le Mans area. With the low basically stationary, periods of showers and thunderstorms will continue through Monday and Tuesday, and likely through Wednesday and possibly Thursday as well. The weather map below shows one model's depiction of the pattern on Wednesday.