Best Time to Drive from Diamond Bar to Lake Forest

Right now (12:51 am PDT): about 37 minutes via SR-241 South and SR-71 North.

Only 42% of this drive is measured by working traffic sensors right now. The rest is estimated from nearby sensors, typical speeds and street traffic, so times can be off. Why so few sensors work.

Typical drive time by departure time

Minutes from Diamond Bar to Lake Forest by day and time you leave (local time)
Leave	5am	6am	7am	8am	9am	10am	11am	12pm	1pm	2pm	3pm	4pm	5pm	6pm	7pm	8pm	9pm
Mon	38	43	44	44	43	43	42	42	41	41	40	40	41	39	39	39	38
Tue	37	43	44	45	44	43	42	41	41	40	40	40	39	38	39	39	37
Wed	37	44	43	44	44	43	42	41	40	40	40	39	39	39	38	38	37
Thu	37	43	42	43	42	43	42	41	41	40	40	39	39	39	39	38	37
Fri	37	42	42	41	40	41	41	41	40	41	40	40	39	39	40	38	37
Sat	37	39	38	39	39	39	39	39	40	40	39	39	39	38	38	38	37
Sun	37	37	38	38	38	39	39	39	39	39	40	39	39	38	38	38	37

About this drive

On weekdays the 40-mile drive from Diamond Bar to Lake Forest (via SR-241 South and SR-71 North) usually takes as little as 37 minutes and up to 45 minutes, when leaving around 8:30 am on Tuesdays. The fastest times to leave are before 6 am or after 1:30 pm. Midday (11 am to 2 pm) it takes about 41 minutes. On weekends it is slowest around 2:30 pm on Saturdays (40 minutes).

About 36 miles of it is freeway, where times follow typical and live traffic from our sensors, and about 3 miles surface streets (5 to 7 minutes on weekdays), estimated from how jammed the freeways around them are at that time. Drive times are measured from central Diamond Bar to central Lake Forest along the route on the map. Starting or ending elsewhere in a big city can add or save several minutes.

Simulated from typical freeway speeds at each point of the drive for the time you would reach it, from every 5-minute reading we have recorded. We don't have sensors on surface streets yet, so the time on them is estimated from how congested the freeways around each end of the drive are at that time, in both directions: streets jam when the freeways do.

Questions

What is the best time to drive from Diamond Bar to Lake Forest?

On weekdays, leave before 6 am or after 1:30 pm. The drive usually takes about 37 minutes then, versus up to 45 minutes at the worst times.

How long does it take to drive from Diamond Bar to Lake Forest?

The 40-mile drive usually takes 37 to 45 minutes on weekdays, depending on when you leave, and about 41 minutes midday.

When is traffic worst from Diamond Bar to Lake Forest?

Leaving around 8:30 am on Tuesdays is usually slowest, about 45 minutes.

Freeways on this drive

SR-241 South in Orange County (16 miles) · SR-71 North in Orange County (6 miles) · SR-60 East in Los Angeles (5 miles) · SR-91 West in Orange County (4 miles) · SR-71 North in Los Angeles (4 miles)

Los Angeles traffic right now · Los Angeles traffic tomorrow · Orange County traffic right now · Orange County traffic tomorrow

More drives

Lake Forest to Diamond Bar (return trip) · Diamond Bar to Los Angeles · Diamond Bar to Long Beach · Diamond Bar to Anaheim · Diamond Bar to Riverside · Diamond Bar to Santa Ana · Diamond Bar to Irvine · Diamond Bar to San Bernardino · Diamond Bar to Fontana · Diamond Bar to Moreno Valley · Diamond Bar to Huntington Beach · Diamond Bar to Glendale

Open the live traffic map →

Leave	5am	6am	7am	8am	9am	10am	11am	12pm	1pm	2pm	3pm	4pm	5pm	6pm	7pm	8pm	9pm
Mon	38	43	44	44	43	43	42	42	41	41	40	40	41	39	39	39	38
Tue	37	43	44	45	44	43	42	41	41	40	40	40	39	38	39	39	37
Wed	37	44	43	44	44	43	42	41	40	40	40	39	39	39	38	38	37
Thu	37	43	42	43	42	43	42	41	41	40	40	39	39	39	39	38	37
Fri	37	42	42	41	40	41	41	41	40	41	40	40	39	39	40	38	37
Sat	37	39	38	39	39	39	39	39	40	40	39	39	39	38	38	38	37
Sun	37	37	38	38	38	39	39	39	39	39	40	39	39	38	38	38	37

Leave	5am	6am	7am	8am	9am	10am	11am	12pm	1pm	2pm	3pm	4pm	5pm	6pm	7pm	8pm	9pm
Mon	38	43	44	44	43	43	42	42	41	41	40	40	41	39	39	39	38
Tue	37	43	44	45	44	43	42	41	41	40	40	40	39	38	39	39	37
Wed	37	44	43	44	44	43	42	41	40	40	40	39	39	39	38	38	37
Thu	37	43	42	43	42	43	42	41	41	40	40	39	39	39	39	38	37
Fri	37	42	42	41	40	41	41	41	40	41	40	40	39	39	40	38	37
Sat	37	39	38	39	39	39	39	39	40	40	39	39	39	38	38	38	37
Sun	37	37	38	38	38	39	39	39	39	39	40	39	39	38	38	38	37

Leave	5am	6am	7am	8am	9am	10am	11am	12pm	1pm	2pm	3pm	4pm	5pm	6pm	7pm	8pm	9pm
Mon	38	43	44	44	43	43	42	42	41	41	40	40	41	39	39	39	38
Tue	37	43	44	45	44	43	42	41	41	40	40	40	39	38	39	39	37
Wed	37	44	43	44	44	43	42	41	40	40	40	39	39	39	38	38	37
Thu	37	43	42	43	42	43	42	41	41	40	40	39	39	39	39	38	37
Fri	37	42	42	41	40	41	41	41	40	41	40	40	39	39	40	38	37
Sat	37	39	38	39	39	39	39	39	40	40	39	39	39	38	38	38	37
Sun	37	37	38	38	38	39	39	39	39	39	40	39	39	38	38	38	37