Empire Mine State Historic Park

Empire Mine State Historic Park is an 827-acre California state park managed by the state park agency, sitting about half a mile from the community of Union Hill. Typical averages from the Grass Valley weather station, about 2 miles away, show a clear seasonal swing. Summer is hot and dry: July highs average around 88°F with lows near 58°F, and July and August each see only about one wet day. Winter is cool and damp, with January highs around 54°F, lows near 33°F, and roughly 12 to 13 wet days a month from December through March. Snow is rare, averaging about one day in February and one in March. Spring and fall offer the mildest middle ground. May brings highs near 71°F, and October brings highs around 72°F, both with relatively few wet days. Several trails start close by, including the Pipeline Trail, Indian Ridge Trail and Upper Union Hill Trail, each about a third of a mile away. Climbers can head to Gravel Wall, about 3.5 miles off. Paddlers will find Deer Creek about 4 miles away.