Six new blazes erupted on Saturday, pushing the total past the 100 mark.
The fires are currently being battled by 30,000 emergency workers, including 140 expert firefighters from Australia and New Zealand.
So far the infernos have overrun more than 1.6 million acres, according to the US National Interagency Coordination Centre.
There are concerns that more fires will start in the coming days.
Parts of the Rocky Mountains are expected to see dry thunderstorms, which see lots of lighting but little rain.
Dry thunderstorms often trigger wildfires in hot conditions.
Meanwhile, parts of the north-west of the US are experiencing a combination of strong winds and low humidity, perfect conditions for fires to start.
Some of the largest fires are in California, where the biggest wildfire in the state’s history is currently raging.
The monster Mendocino Complex Fire, to the north of the state, has already consumed over 300,000 acres.
In southern California another fire, dubbed the “Holy Fire”, has forced over 21,000 people to leave their homes.
However by Sunday around 30% of the inferno had been contained.
A 51 year-old man has been arrested and appeared in court accused of deliberately starting the blaze.
California Fire Battalion Chief Jonathan cox said: “We are making good strides in containment on a lot of these fires.
“The tide is turning.”
A study by the University of Colorado Boulder last year found that around 84 percent of wildfires are started directly or indirectly by humans.
This includes fires triggered by power line sparks, campfires and deliberate arson.