Last year, in early June both the Alaska Highway and Cassiar were closed due to flooding and washouts. By July floodwatch is usually over.
The washout on the Alaska Highway was near Rancheria; it was a four-day closure. At the same time the Cassiar and Campbell Highway were closed due to flooding so NO traffic was moving south or north, including the trucks that deliver fuel and groceries to the north!
In 2011, Hwy 97 had numerous slides due to rain between Prince George and Dawson Creek. The highway was closed for an extended period. Folks had to detour into Alberta or take the Cassiar northward.
In July & August, it transitions to forest fire season. The Cassiar has closed several times in past years due to forest fires along the north end of the highway.
Keep your eyes on the road reports and keep your fingers crossed.
Also keep your RV's pantry stocked with basics just in case you experience a delay.