Broadleaf weed problems?

As Labor Day approaches, you are likely forced to think about school resuming and the sad state of affairs with your lawn.  If you have an average lawn in New Hampshire or Vermont, you are likely going to find fat broadleaf weeds like plantain, dandelions, and clover among a host of other weedy villains.  Let us not forget to give tribute to the massive crop of crabgrass which has now grown into your driveway, patio, and walkway cracks!  You my friend have lawn problems!  What to do?  Something that can be done!
If you attempted to treat for weeds this summer, your efforts were most likely in vain due to high temperatures and dry conditions.  Broadleaf weeds are best reduced when they are actively growing which usually occurs with cool fall or spring weather when soil moisture is adequate.  Any summer spraying usually just causes the surrounding turf to brown under the stress and the weed itself might look a worse for wear but does not die.
This year brought such unusually hot and dry weather, attempting to keep a lawn free of weeds and especially crabgrass seemed like spraying a house on fire with a garden house.  While proper mowing does help, irrigation became vital if your well supported the flow or your town did not put a watering ban in effect.  Brown grass caused the soil to heat up quickly where dormant crabgrass and annual weed seeds popped up and grew overnight, basking in the hot noon sun.  That is the past and explains why your lawn may look the way it does today, even with professional care.
Moving forward, you have two main options, renovate and repair damaged lawn areas to regain lost lawn or go after the weeds once we get cooler, wetter weather.  My advice to most folks is to aerate and seed in the fall and repair any lawn damage without the pressure of crabgrass and annual weeds, that are now dying (something about them dying in the fall).
With reduced competition, fall becomes the best time to overseed and aerate a lawn after a brutal New England growing season.  Go after the weeds next spring when seeding is less effective and crabgrass lurks, just waiting to over run your best efforts in lawn repair.  There is little time now to spray for weeds and seed, given most weed control products have a one month waiting period before seeding is recommended.
My advice for the average home owner is to get as much grass back now and then deal with the weeds next spring.  Try improving the soil quality by adding sea kelp or compost tea to get an edge next spring.  The next few months are critical and should be taken full advantage of if you really want to make a difference in your home lawn; not only this fall but to set the stage for the entire growing season of 2013!