Juniper turning brown
Your tree looks dead. I'd remove it.
Since your photo doesn't show a closeup of the needles or an area of the tree where the damage is just starting, I can't offer a guess as to what happened. Many factors can cause browning of needles: disease, winter damage, shade tree decline, insects. Here is a diagnostic site:
You might want to have a certified arborist look at it before you take it down, since your other trees may be at risk: