The company now expects costs for the year of $3.8 billion to $4.1 billion after-tax, compared with $1 billion to $1.4 billion seen earlier.
The San Francisco-based utility filed for bankruptcy this past January, citing potential liabilities of more than $30 billion stemming from the wildfires.
The forecast includes about $1.51 billion to $1.48 billion in costs for the 2017 Northern California wildfires and $1.61 billion to $1.58 billion related to the 2018 Camp Fire blaze.
The Camp Fire wildfire erupted in November of 2018, destroyed nearly 19,000 homes and killed 85 - making it the deadliest single wildfire in California history.
In May, state fire investigators determined that PG&E transmission lines caused the fire.
The company on Friday reported a wider net loss attributable to shareholders of $2.55 billion or $4.83 per share in the quarter ended June 30, from $984 million or $1.91 per share, a year earlier. (https://bit.ly/2TimI7S)
The loss was mainly from a $3.9 billion pre-tax charge for estimated third-party claims related to the wildfires.
Excluding items, the company reported a profit of $1.10 per share, beating analysts' estimates of 98 cents, according to IBES data from Refinitiv.
Total operating revenue fell to $3.94 billion from $4.23 billion.
(Reporting by Shanti S Nair in Bengaluru; Editing by Bernard Orr)