Periods of heavy rain with a chance of thunderstorms until early Saturday morning. Localised downpours of 25 to 40 mm per hour are possible, especially inland. More widespread heavy rain is expected from Sunday afternoon, especially about the Wairoa District. There is a high chance a warning will be issued for at least some of the area on Sunday. Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible. Chance of upgrading to a Warning: High.