HOLLYWOOD So far, so good this summer for the broadcast nets, which for the first time in three years are delivering more viewers than the previous season.

We’re only three weeks into television’s warm-weather session, but there are signs that an increased output of original programming — including promising newcomers like Fox’s “American Juniors” and NBC’s “Last Comic Standing” — is helping broadcasters stem the tide in the months when cable has come to dominate.

Ad-supported cable as a group still holds a sizable advantage over the six broadcast nets during summer, but the gap is now closing.

According to Nielsen data for the first three full weeks of summer (May 26-June 15), basic cable was averaging 45.7million viewers and a 50 share of the primetime aud, while the six broadcast nets averaged 36.3 million and a 40 share. The nets were up 4% and gained 2 share points, while basic cable was flat.

And the wealth is spread around, with five of the six broadcast nets up vs. the same period a year ago, led by Fox’s 21% gain. The top 10 cable networks, on the other hand, are down 10% vs. a year ago.

The only broadcaster showing losses is NBC, which carried the NBA Playoffs last season and is down 13% in total viewers and 20% in 18-49 without it. The Peacock is up more than 10% vs. last summer, though, if you count only series programming, and is the summer leader in key categories, including 18-49 (3.2/10).

The most impressive summer rookie is Fox’s “American Juniors,” a spinoff of monster hit “American Idol.” The show, which focuses on wannabe singers under the age of 16, has led its Tuesday-at-8 slot with its first three tries, averaging a 13 share in adults 18-49.

Also looking good is “Last Comic Standing,” which won its Tuesday-at-9 slot the first two weeks out. NBC’s “Fame” started strong but faded, while the same net’s dating show “For Love or Money” and courtroom reality hour “Crime and Punishment” join CBS’ “Amazing Race 4” as solid but unspectacular players.

Repeats of scripted hits remain a summer staple, with three 9 o’clock comedy anchors — CBS’ “Everybody Loves Raymond,” ABC’s “According to Jim” and NBC’s “Will & Grace” — delivering impressive perfs. Auds may be catching up on missed episodes of these faves, which faced some brutal competish on TV during the regular season.

On a net-by-net basis, ABC is up the most vs. last year in 18-49 (18% to a 2.6/8) but this is mostly on the back of the NBA Finals, which ranked as the lowest on record for primetime (9.9 million viewers), but provided the net with a jolt.

The Alphabet is also doing well with repeats of its top comedies, but overall is expected to fall well behind its rivals in July without the help of hoops and with little in the way of unscripted fare.

Fox has improved greatly since its weak start last summer, up 17% in adults 18-49 (second-place 2.7/9) and 30% in adults 18-34 (first-place 3.0/11).

Much of its early gains are coming on Monday, where “Boston Public” and “Ally McBeal” repeated poorly last summer. It was about this time last year that “American Idol” took off, though, so its year-to-year comparisons will soon not be looking as good.

CBS is up 9% in 18-49 (2.5/8) even though the bulk of its original programming (“Big Brother 4” and dating contest show “Cupid”) won’t bow until July. Net’s top crime dramas (“CSI,” “CSI: Miami” and “Without a Trace”) all repeat pretty well, with “Trace” up more than 30% over last year’s “The Agency” on Thursday.

UPN is up 8% in 18-49 (1.3/4), boosted by contest show “America’s Next Top Model,” while The WB was flat (1.1/4) but hopeful that contest surfing show “Boarding House: North Shore,” which launched last week, can turn up the heat.