When it’s hot enough to make our eardrums sweat, we count on R&B to deliver the summer jams that’ll get us through.

The beats are always bold, guiding our bodies through steamy, sticky dance floors. The lyrics are always lovelorn, guiding our hearts through a cold and lonely universe.

Remember when Beyonce fell “Crazy in Love” in 2003? So awesome. But this summer, she’s sleepwalking through her new music video like a Stepford wife. In 2007, Rihanna had us all crowding beneath that “Umbrella.” Now, she’s pushing a limp reggae single, “Man Down.”

We’re all down. Searching for R&B heat on this summer’s airwaves only leads to more downers, more dead ends, more brain freeze, more return trips into the over-tattooed arms of Chris Brown or Trey Songz or Lloyd. And they’re all wearing too much cologne. Eternity for men. Disgusting.

Feeling adrift in the cruelty of existence, we do what we always do. We go online.

That’s where free digital albums from Frank Ocean, the Weeknd and Jhene Aiko have been lurking for months — a secret bumper crop of superb, subterranean R&B. The lyrics are heavy, but the melodies are made of Freon. The drum machines beat softly, like drippy window unit air conditioners. It all sounds as if it was recorded at the loneliest hours of the night. None of it sounds like the vintage heat of Beyonce or any summer you can remember.

Since March, spasms of buzz surrounding these acts have leveled into an ascendant hum, with Ocean’s airy single, “Novacane,” actually making the leap from the blogosphere to mainstream radio.

The rest of his self-leaked album, “Nostalgia, Ultra” — set for commercial rerelease as a truncated EP on Tuesday — is both dreamlike and disillusioned, sung with a whimsical cool that could temper the hottest of hotheads. (In addition to crooning alongside petulant L.A. rap crew Odd Future, Ocean has also been involved in Jay-Z and Kanye West’s still-in-the-works collaboration disc “Watch the Throne.”)

Much of this summer’s R&B cold front can be traced directly back to West. His chilling 2008 album “808s and Heartbreak” captured the acute loneliness of living in a hyper-connected world. Two years later, singer-rapper Drake transposed West’s isolationism into the most promising new career in hip-hop.

Now, Toronto singer Abel Tesfaye, who records as the Weeknd, is expanding on Drake’s tales of fame and misfortune with more sex, more drugs and more disenchantment. His “House of Balloons” album arrived online in March, both glassy-eyed and misty-eyed, druggy and forlorn. During “Wicked Games,” his voice trembles: “Bring your love, baby, I can bring my shame/Bring the drugs, baby, I can bring my pain.”

“House of Balloons” currently stands as the most compelling R&B release of the year — and Tesfaye has promised two more albums before 2011 is up.

Elsewhere in blogland, there’s “Swear,” a song by Inc., two Los Angeles brothers who got their start recording and touring with the likes of 50 Cent, Beck and Elton John. “Swear” sounds like an ethereal mid-career Prince hit, valiantly trying to kickstart itself back to life. It anchors a three-song EP due out July 26.

Aiko hasn’t earned as much attention as Ocean or the Weeknd, but her music bears similar sonic fingerprints. The 14 tracks on “Sailing Soul(s)” sound as if they’re coated in digital frost. Her voice is cool and distant, but the lyrics fall from her lips with so much sibilance, you can practically feel the girl breathing in your ear.

It sounds like she’s right there, but Aiko makes it clear she’s all alone. On “Real NOW,” she’s either jotting in her journal or taking notes for her therapist: “Faking these smiles too often, I do not cry that often, I need to cry more often . . . I’m the only real I see.”

Things stay real during the dreamy drip of “July” as she mourns a romance turned icy. “Now it’s getting colder,” she coos. “Lips are turning colors.”

Jot it in your journal: 2011, the summer that R&B made our lips as blue as our hearts.