Republicans will keep control of the US Senate in the November 6, 2018 midterms (just over 80%).

Accurate ●●●●●

“(Republican odds of keeping the Senate are also just north of 80 percent in a nice bit of symmetry.)”

Said on: 5 November 2018 · FiveThirtyEight final 2018 midterm forecast article (mirrored on Goodreads)
Source: Final Election Update: Democrats Aren't Certain To Take The House, But They're Pretty Clear Favorites · FiveThirtyEight (via Goodreads blog mirror)
Should come true: 6 Nov 2018
How sure they sounded: just north of 80 percent
Categories: Elections
Importance: 3 of 5 · Senate control decides confirmations and legislation.

Outcome

Accurate Happened 6 November 2018.

Republicans kept the Senate in 2018 and expanded their majority from 51 to 53 seats, matching Silver's ~80% forecast.

Evidence:

History