By: Stephen McCoy

For the past three races of the Rolex 24 hours of Daytona, there’s been periods of rain that have been bothersome to teams, drivers, track officials, and fans. But the rain seen at the 2019 iteration stands out from the previous two years. A veritable deluge of precipitation began in the 4:00-5:00 hour on Sunday and refused to let up, causing IMSA to call the race ten minutes before the conclusion of 24 hours after two red flag periods with multiple full course yellows in between. The question though is why all the rain? What made this year’s weather conditions so different than those seen recently?

To begin, I’ll look at the atmosphere on Saturday night.

Looking at the latest high resolution models, we could have rain moving into the Daytona Beach area, including the speedway, starting as early as around 3:00 am. Precipitation may start off as a passing light shower or sprinkles, but by 5:00 am, light to moderate rainfall can be expected through the remainder of the race.

We could see rainfall totals around or just over 1/4-inch through noon and possibly another 1/4-in from noon to the checkered flag. Unfortunately, rainfall could be heavy enough to cause a few caution flags, especially after the noon hour. The only good news is that the air will be stable enough for lightning to not occur.

So, here is the break down in times...

9:00 pm:  Mostly cloudy and dry. Around 53 degrees. Winds out of the north-northeast at 5-10 MPH.

12:00 am:  Cloudy and dry. Around 53 degrees. Winds out of the north-northeast at 5-10 MPH.

3:00 am:  Cloudy with a chance of showers. Around 52 degrees. Winds out of the northeast at 5-10 MPH. Chance of rain around 40%.

6:00 am:  Cloudy with rain likely. Around 50 degrees. Winds out of the north-northeast at 10-15 MPH with possible gusts up to 20 MPH. Chance of rain 100%.

9:00 am:  Cloudy with rain likely. Around 53 degrees. Winds out of the north-northeast at 10-15 MPH with possible gusts up to 25 MPH. Chance of rain 100%.

12:00 pm:  Cloudy with rain likely. Around 56 degrees. Winds out of the north at 10-15 MPH with possible gusts up to 30 MPH. Chance of rain 100%.

Checkered Flag:  Cloudy with rain likely. Around 56 degrees. Winds out of the north at 10-20 MPH with possible gusts up to 30 MPH. Chance of rain 100%.

While it is exciting to see the best racers in the world racing in wet conditions, rain may be too hard at times for the race to be put under the caution flag a few times. I'm crossing my fingers that it doesn't get to the point of stopping the cars.

Our radar continues to run on our website. If viewing on a mobile device, it is best to select the "web" view at the bottom of the page. I'll be working on a more web-friendly version throughout the next few weeks.

Prior to the beginning of the race, the morning will start off in the mid-40s at 8:00 am underneath mostly sunny skies. The temperature will quickly rise into the lower 60s at noon before falling back a degree or two before the start.

Green flag takes place at 2:35 pm EST and there will be no weather worries for the first half of the race. Skies will be mostly sunny with temperatures in the lower 60s at the start, but clouds will slowly be on the increase and those temperatures will eventually begin to drop into the lower 50s by 7:00 PM and will be close to 50 degrees by midnight with mostly cloudy skies.

The system may be close enough to the track that a stray shower or two could pass over, but those chance remain very small through the rest of the pre-dawn hours. Those shower chances will be on the increase as we pass sunrise, unfortunately becoming likely by 8:00 am and through the rest of the race. At this point, the rainfall doesn't look all that heavy with amounts possibly topping out around 1/4 inch by the checkered flag.

Sunday's temperatures will start off around 50 degrees at midnight and only drop into the upper 40s by 8:00 am, then quickly rising to around 60 degrees by 1:00 pm. It should be close to 60 degrees at the checkered flag with rain likely.

The good news is that there should not be any lightning in the area throughout the race and rainfall shouldn't be heavy enough to cause any stoppages, but may be enough for a caution flag or two. Winds throughout the race will start off out of the northeast at 6-12 MPH from start through midnight, then picking up 8-16 MPH out of the north after midnight with gusts up to 20 MPH possible near the finish.

Radar continues to be up and running. If pulling the radar up on a mobile device, please be sure to select the web version at the bottom of the page. Radar will automatically refresh.

After a morning round of thunderstorms on Thursday followed by slowly clearing skies throughout the rest of the day, the weather will be much improved but much cooler for Friday. Temperatures will start off in the lower 40s at daybreak and climb into the upper 50s to near 60 degrees for the afternoon high underneath sunny skies. Winds will be out of the northwest to the north at 6-12 MPH.

On Saturday, we'll have a few more clouds in the skies over Daytona International Speedway, but not enough to keep plenty of sun shining on you to help warm you a little. Temperatures at daybreak will be in the lower 40s and will top out in the upper 50s to near 60 degrees around 1:00 pm. Temperatures will start to slowly head downward after that, reaching the lower 50s by 8:00 pm, and the upper 40s by midnight. Winds will be out of the north to northeast at 6-12 MPH.

During the overnight hours, some clouds will start to build in and skies will become mostly cloudy before daybreak on Sunday. There will be a system that will be passing by just to the south of the speedway affecting southern Florida, but may be just close enough to send one or two very light showers across the track at any point afer daybreak through the end of the race. The chance of rain affecting the track is only 20%, and if any does fall, amounts will be less than 0.10 inches. Temperatures at sunrise will be in the mid-40s and will rise into the mid-50s by 11:00 am, and eventually into the upper 50s to near 60 degrees by the checkered flag. Winds will be out of the north at 6-12 MPH.

Radar will be up and running throughout the event weekend, so we'll see any shower if they pop up on Sunday.

On Thursday, a cold front will be working through the southeastern United States with showers and thunderstorms out ahead of it. For the Daytona Beach area, showers and a few claps of thunder look to be likely during the early morning hours at the track. The good news is that the activity looks to come to an end around or just after the noon hour. Skies will begin to slowly clear and will be mostly clear by sunset. Winds will be out of the southwest at 10-15 MPH to start, but will shift more out of the west by the afternoon. The afternoon will be mild with the high reaching the lower 70s.

Friday will be a very nice but cool day in the Daytona Beach area. Skies will be full of sunshine but those jackets may be needed for the morning hours and possibly throughout the day as winds will be out of the north at 5-10 MPH. After starting off in the mid-40s at sunrise, expect the afternoon highs to only top out in the upper 50s.

Saturday will be a sunny day at Daytona International Speedway with temperatures starting off in the mid-40s at sunrise. The good news is that we'll make it up into the lower 60s for the afternoon high, but winds will continue to be out of the north to northeast at 5-10 MPH. For the evening and into the late night hours, skies will remain clear but temperatures will not drop all that much, making it into the lower 50s by midnight.

We'll have some clouds start to roll in during the pre-dawn hours on Sunday and early morning lows will only bottom out in the lower 50s at sunrise. Skies will be mostly cloudy by sunrise and through the rest of the daylight hours at the track, but we'll stay dry through the end of the race. Winds will shift from out of the north to out of the west at 2-7 MPH. Afternoon high will make it up into the lower 60s.