B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 822
Workload
Ground Event / Encounter Ground Strike - Aircraft
Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control; General Maintenance Action
Weather
This was the second leg of the first day of our trip. First Officer (FO) was flying pilot. LAS was night; T 40 C; winds on ATIS 070/12/ but tower winds 360/5. FO flew a stable visual/ILS approach to RWY 26L LAS. We intercepted GS at 7000. Approach was stable; and FO crossed the threshold target speed plus a few knots and on glidepath.  Just prior to crossing the paved surface; the FO remarked that he anticipated a thermal that comes every time you land in Vegas. Sure enough; as soon as we crossed over the paved surface; at approximately 100-80 feet AGL; we had a sudden wing rock that felt like a wake turbulence event but seemed more in line with a thermal event as anticipated by the FO. We were spaced 3-4 miles in trail of an Airbus 319. The FO recovered nicely from this short but abrupt disruption and landed. I remarked on landing roll 'nice recovery' and did not even consider that we had scraped the tail on landing. I never felt the situation was unsafe or warranted a go around and felt the FO did a great job executing the approach and landing. It was only upon reaching the gate that an aft Flight Attendant (FA) called and informed us that he felt we scraped the tail. Upon inspection of the tail; we found that we in fact scraped the paint off the skid but did not compress the strut. We checked ACARS and found the pitch attitude at landing was 7.6; which was under the 8.3 considered probable for tail contact. We made a logbook write up; contacted Maintenance; the Operations Manager and an Ops Report was filed.
B737 Captain reported aircraft encountered a thermal downdraft causing a tail strike while landing.