ABC’s “The Bachelorette”  picked up steam Monday one week from its conclusion, hitting season highs and teaming with drama “Mistresses” for the net’s best summer showing on the night in more than a year. CBS still claimed Monday’s top show with “Under the Dome,” which was just about on par with last week.

According to preliminary national estimates from Nielsen, a teary episode of “The Bachelorette,” which saw one of the three finalists bow out of the competition before the rose ceremony, surged to a 2.3 rating/7 share in adults 18-49 and 7.8 million viewers overall, up 21% (0.4) from last week and winning each half-hour from 8 to 10. It was followed by rookie drama “Mistresses” (1.3/4 in 18-49, 4.1 million viewers overall), which appears to be up for a second straight week and hit a best-yet 1.1/3 in adults 18-34; and it again provided the net with nice time-period improvement over last year.

ABC won the night in key demos and also edged out CBS in total viewers.

At CBS, “Under the Dome” (2.7/8 in 18-49, 11.1 million viewers overall) was off a smidge from last week but again dominated its timeslot and was the night’s No. 1 program overall. Earlier, the net aired repeats of comedies “How I Met Your Mother” (1.1/4 in 18-49, 3.5 million viewers overall), a special “Mike & Molly” at a special time (1.1/3 in 18-49, 3.9 million viewers overall), “2 Broke Girls” (1.3/4 in 18-49, 4.6 million viewers overall) and “Mike & Molly” in its regular slot (1.3/4 in 18-49, 5.0 million viewers overall).

NBC’s “American Ninja Warrior” (1.5/5 in 18-49, 5.2 million viewers overall) and “Get Out Alive With Bear Grylls” (1.2/3 in 18-49, 3.7 million viewers overall) were both down from last week to season lows, though they again led their hours in key male demos. And at 10, the struggling “Siberia” (0.7/2 in 18-49, 2.0 million viewers overall) was down a tick from its most recent original of two weeks ago.

Fox ran a distant fourth among the Big Four with encores of “Raising Hope” (averaging 0.6/2 in 18-49, 1.7 million viewers overall for two episodes), “New Girl” (0.5/2 in 18-49, 1.4 million viewers overall) and “The Mindy Project” (0.5/1 in 18-49, 1.2 million viewers overall).

At Univision, the premiere of 9 p.m. telenovela “La Tempestad” (The Storm) averaged a 1.4/4 in 18-49 and 3.5 million viewers overall, nearly in line with lead-in “Porque el Amor Manda” (1.5/5 in 18-49, 3.5 million viewers overall).

Preliminary 18-49 averages for the night: ABC, 2.0/6; CBS, 1.7/5; Univision, 1.3/4; NBC, 1.1/3; Telemundo, 0.7/2; Fox, 0.5/2; CW, 0.2/1.

In total viewers: ABC, 6.6 million; CBS, 6.5 million; NBC, 3.6 million; Univision, 3.3 million; Telemundo, 1.6 million; Fox, 1.5 million; CW, 0.7 million.