It’s almost time for one of the greatest traditions in the city of Boston, and we have an early first look at how the weather might play out during the 129th Boston Marathon on Monday, April 21.

We’re almost a week away from the big race, but we’re starting to see a few trends develop that will give runners and wheelchair participants an idea of what the weather might be like by the time the sneakers and wheels hit the pavement for the 26.2-mile race route. Last year saw temperatures soar into the 70s under sunny skies, but this year is looking cooler.

We’re well within the window where reliable long-term weather models — the GFS and the European models — can be studied. Both have decent accuracy beyond 10 days, but with spring in full flex, we still need to keep in mind that the spring weather pattern can be tricky and will continue to be active leading up to marathon day.

So far, there is agreement between the two models that points toward a trough pushing into New England and leading to temperatures running at average about 5 degrees cooler than the daily average high of 59, which would be pretty ideal running temperatures for the race.

The concern is that this cooldown would be marked by a storm system moving that could bring the chance for rain into the region just before the race or in the afternoon on race day — although the models are split on the timing and storm track this far out. The marathon starts at 9:06 a.m. for the wheelchair races and 9:37 a.m. for runners.

The GFS model is pointing to an area of low pressure that will push through the interior of New England Monday afternoon, bringing the chance for scattered showers along the race route, starting in the early afternoon, around 1 p.m. An offshore high pressure may build strong enough to slow down the approaching system and hold off any rainfall until Monday night.

Meanwhile, the Euro model has the storm system riding along the boundary of the offshore high pressure, bringing precipitation through New England on Sunday and clearing out before the start of the marathon.

At this point, it’s too early to gauge how strong the winds will be, but a looming low-pressure system might lock in some breezy conditions as a pressure gradient establishes between the nearby storm and offshore high. Both models agree that the low will be relatively weak, which suggests that we might only feel a slight breeze on race day.

Here’s an early look at what marathon day could look like in the morning and afternoon:

• 6 a.m to noon — There’s a chance for the morning to start warmer than normal before the cooler air kicks in, depending on where the storm tracks. If it stays further inland, then a southerly flow could hang on long enough that temperatures could range between 50 and 55 degrees as the race begins.

Should the system already clear out by starting time, then we could see runners begin with temperatures closer to the mid-40s under decreasing clouds through the morning.

• Noon to 6 p.m. — The afternoon and early evening will be a few degrees below average, between both of the models, with highs closer to the mid-50s along the route. Should the GFS model run come to fruition, then showers will enter the picture between 3 p.m. and 6 p.m.

Ultimately, the long-term forecast models provide preliminary clues to the weather we can expect on race day, but not with pinpoint accuracy. We will continue to monitor the weather leading up to and on Monday.

The average daily high over the past 10 marathons has been 63 degrees. The years 2017, 2020, 2021, and last year all soared above 70.

The coldest marathon day was in 2015, with the high reaching only 46 degrees. Four of the last 10 marathons saw rain, with 2023 being the last year the course ran wet.

Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.

It’s almost time for one of the greatest traditions in the city of Boston, and we have an early first look at how the weather might play out during the 129th Boston Marathon on Monday, April 21.

We’re almost a week away from the big race, but we’re starting to see a few trends develop that will give runners and wheelchair participants an idea of what the weather might be like by the time the sneakers and wheels hit the pavement for the 26.2-mile race route. Last year saw temperatures soar into the 70s under sunny skies, but this year is looking cooler.

We’re well within the window where reliable long-term weather models — the GFS and the European models — can be studied. Both have decent accuracy beyond 10 days, but with spring in full flex, we still need to keep in mind that the spring weather pattern can be tricky and will continue to be active leading up to marathon day.

So far, there is agreement between the two models that points toward a trough pushing into New England and leading to temperatures running at average about 5 degrees cooler than the daily average high of 59, which would be pretty ideal running temperatures for the race.

The concern is that this cooldown would be marked by a storm system moving that could bring the chance for rain into the region just before the race or in the afternoon on race day — although the models are split on the timing and storm track this far out. The marathon starts at 9:06 a.m. for the wheelchair races and 9:37 a.m. for runners.

The GFS model is pointing to an area of low pressure that will push through the interior of New England Monday afternoon, bringing the chance for scattered showers along the race route, starting in the early afternoon, around 1 p.m. An offshore high pressure may build strong enough to slow down the approaching system and hold off any rainfall until Monday night.

Meanwhile, the Euro model has the storm system riding along the boundary of the offshore high pressure, bringing precipitation through New England on Sunday and clearing out before the start of the marathon.

At this point, it’s too early to gauge how strong the winds will be, but a looming low-pressure system might lock in some breezy conditions as a pressure gradient establishes between the nearby storm and offshore high. Both models agree that the low will be relatively weak, which suggests that we might only feel a slight breeze on race day.

Here’s an early look at what marathon day could look like in the morning and afternoon:

• 6 a.m to noon — There’s a chance for the morning to start warmer than normal before the cooler air kicks in, depending on where the storm tracks. If it stays further inland, then a southerly flow could hang on long enough that temperatures could range between 50 and 55 degrees as the race begins.

Should the system already clear out by starting time, then we could see runners begin with temperatures closer to the mid-40s under decreasing clouds through the morning.

• Noon to 6 p.m. — The afternoon and early evening will be a few degrees below average, between both of the models, with highs closer to the mid-50s along the route. Should the GFS model run come to fruition, then showers will enter the picture between 3 p.m. and 6 p.m.

Ultimately, the long-term forecast models provide preliminary clues to the weather we can expect on race day, but not with pinpoint accuracy. We will continue to monitor the weather leading up to and on Monday.

The average daily high over the past 10 marathons has been 63 degrees. The years 2017, 2020, 2021, and last year all soared above 70.

The coldest marathon day was in 2015, with the high reaching only 46 degrees. Four of the last 10 marathons saw rain, with 2023 being the last year the course ran wet.

Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.

It’s almost time for one of the greatest traditions in the city of Boston, and we have an early first look at how the weather might play out during the 129th Boston Marathon on Monday, April 21.

We’re almost a week away from the big race, but we’re starting to see a few trends develop that will give runners and wheelchair participants an idea of what the weather might be like by the time the sneakers and wheels hit the pavement for the 26.2-mile race route. Last year saw temperatures soar into the 70s under sunny skies, but this year is looking cooler.

We’re well within the window where reliable long-term weather models — the GFS and the European models — can be studied. Both have decent accuracy beyond 10 days, but with spring in full flex, we still need to keep in mind that the spring weather pattern can be tricky and will continue to be active leading up to marathon day.

So far, there is agreement between the two models that points toward a trough pushing into New England and leading to temperatures running at average about 5 degrees cooler than the daily average high of 59, which would be pretty ideal running temperatures for the race.

The concern is that this cooldown would be marked by a storm system moving that could bring the chance for rain into the region just before the race or in the afternoon on race day — although the models are split on the timing and storm track this far out. The marathon starts at 9:06 a.m. for the wheelchair races and 9:37 a.m. for runners.

The GFS model is pointing to an area of low pressure that will push through the interior of New England Monday afternoon, bringing the chance for scattered showers along the race route, starting in the early afternoon, around 1 p.m. An offshore high pressure may build strong enough to slow down the approaching system and hold off any rainfall until Monday night.

Meanwhile, the Euro model has the storm system riding along the boundary of the offshore high pressure, bringing precipitation through New England on Sunday and clearing out before the start of the marathon.

At this point, it’s too early to gauge how strong the winds will be, but a looming low-pressure system might lock in some breezy conditions as a pressure gradient establishes between the nearby storm and offshore high. Both models agree that the low will be relatively weak, which suggests that we might only feel a slight breeze on race day.

Here’s an early look at what marathon day could look like in the morning and afternoon:

• 6 a.m to noon — There’s a chance for the morning to start warmer than normal before the cooler air kicks in, depending on where the storm tracks. If it stays further inland, then a southerly flow could hang on long enough that temperatures could range between 50 and 55 degrees as the race begins.

Should the system already clear out by starting time, then we could see runners begin with temperatures closer to the mid-40s under decreasing clouds through the morning.

• Noon to 6 p.m. — The afternoon and early evening will be a few degrees below average, between both of the models, with highs closer to the mid-50s along the route. Should the GFS model run come to fruition, then showers will enter the picture between 3 p.m. and 6 p.m.

Ultimately, the long-term forecast models provide preliminary clues to the weather we can expect on race day, but not with pinpoint accuracy. We will continue to monitor the weather leading up to and on Monday.

The average daily high over the past 10 marathons has been 63 degrees. The years 2017, 2020, 2021, and last year all soared above 70.

The coldest marathon day was in 2015, with the high reaching only 46 degrees. Four of the last 10 marathons saw rain, with 2023 being the last year the course ran wet.

Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.

It’s almost time for one of the greatest traditions in the city of Boston, and we have an early first look at how the weather might play out during the 129th Boston Marathon on Monday, April 21.

We’re almost a week away from the big race, but we’re starting to see a few trends develop that will give runners and wheelchair participants an idea of what the weather might be like by the time the sneakers and wheels hit the pavement for the 26.2-mile race route. Last year saw temperatures soar into the 70s under sunny skies, but this year is looking cooler.

We’re well within the window where reliable long-term weather models — the GFS and the European models — can be studied. Both have decent accuracy beyond 10 days, but with spring in full flex, we still need to keep in mind that the spring weather pattern can be tricky and will continue to be active leading up to marathon day.

So far, there is agreement between the two models that points toward a trough pushing into New England and leading to temperatures running at average about 5 degrees cooler than the daily average high of 59, which would be pretty ideal running temperatures for the race.

The concern is that this cooldown would be marked by a storm system moving that could bring the chance for rain into the region just before the race or in the afternoon on race day — although the models are split on the timing and storm track this far out. The marathon starts at 9:06 a.m. for the wheelchair races and 9:37 a.m. for runners.

The GFS model is pointing to an area of low pressure that will push through the interior of New England Monday afternoon, bringing the chance for scattered showers along the race route, starting in the early afternoon, around 1 p.m. An offshore high pressure may build strong enough to slow down the approaching system and hold off any rainfall until Monday night.

Meanwhile, the Euro model has the storm system riding along the boundary of the offshore high pressure, bringing precipitation through New England on Sunday and clearing out before the start of the marathon.

At this point, it’s too early to gauge how strong the winds will be, but a looming low-pressure system might lock in some breezy conditions as a pressure gradient establishes between the nearby storm and offshore high. Both models agree that the low will be relatively weak, which suggests that we might only feel a slight breeze on race day.

Here’s an early look at what marathon day could look like in the morning and afternoon:

• 6 a.m to noon — There’s a chance for the morning to start warmer than normal before the cooler air kicks in, depending on where the storm tracks. If it stays further inland, then a southerly flow could hang on long enough that temperatures could range between 50 and 55 degrees as the race begins.

Should the system already clear out by starting time, then we could see runners begin with temperatures closer to the mid-40s under decreasing clouds through the morning.

• Noon to 6 p.m. — The afternoon and early evening will be a few degrees below average, between both of the models, with highs closer to the mid-50s along the route. Should the GFS model run come to fruition, then showers will enter the picture between 3 p.m. and 6 p.m.

Ultimately, the long-term forecast models provide preliminary clues to the weather we can expect on race day, but not with pinpoint accuracy. We will continue to monitor the weather leading up to and on Monday.

The average daily high over the past 10 marathons has been 63 degrees. The years 2017, 2020, 2021, and last year all soared above 70.

The coldest marathon day was in 2015, with the high reaching only 46 degrees. Four of the last 10 marathons saw rain, with 2023 being the last year the course ran wet.

Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.