The Reserve Bank of Australia (RBA) is all set to cut the interest rate in May, regardless of first-quarter inflation data due this week, Westpac said on April 24.

"The turmoil abroad has...changed the game and flipped the risks. You can lock in a 25bp cut in May, even if the Q1 inflation data are a shade disappointing," wrote Westpac chief economist Luci Ellis in a note.

Westpac echoes market expectations for the RBA to lower the official cash rate to 3.85% on May 20 to take into account the impact of the US' tariff policies on economic growth.

The bank expects the RBA to cut the rate three more times this year, including the one in May.

"However, the risks on timing and extent are now skewed to the RBA moving faster than this and/or going further," Ellis wrote.

The official inflation report for the first quarter is due on April 30.