From Dr. Jim Murphy on the Rutgers TurfBlog:
Aeration during the summer can be a helpful practice but does need some caution. Many turf managers performing mid-season aeration on putting greens will be using needle tines, which are less disruptive. But the key words are “less disruptive”; as reminder, needle time aeration (venting) will cause some damage to the roots. How extensive the root system is and how you manage for any “venting stress” makes a difference in how well the practice of venting works for you. Some things to think about and prepare for include:
How extensive is the current root system? Turf with a shallow/limited root system will be more sensitive to the disruption from venting and other cultivation practices than a turf with an extensive root system.
If dry (single digits on TDR 300/350 probes), suggest that water content of putting greens be increased into the lower-teens with irrigation the night before venting is performed.
If hot (90 °F / 32 °C or more), aerate with needle tines during the morning and/or evening avoiding the heat of the day (12:00-3:00 PM).
If 1 and/or 2 are non-ideal, consider a shallow depth of venting (3 to 4 inches/75 to 100 mm) to reduce damage to root system and therefore lessen “drought” stress caused by venting. Remember, damage to the root system from venting/aeration/cultivation does happen; be prepared for it.
If depth of aeration is not reduced and it is dry and/or hot, lightly irrigate (up to 0.1-inch/2.5-mm) immediately after needle tine aeration to reduce any drought stress resulting from root pruning caused by needle tine aeration.
Roll after needle aeration and light irrigation, if performed, to regain smoothness of the putting surfaces.
Perform nighttime irrigation (50 to 80% ET) after needle tine aeration and be prepared to manage any sooner than normal expression of drought stress in putting greens over the next few days. Any strong drought stress symptoms are likely to occur in localized areas rather than the entire putting surface.
Best wishes for a great finish to the season!