What factors are driving the AUD/JPY surge to 35-year highs, and how is the Bank of Japan's increasingly hawkish stance — including calls for faster rate hikes and recent yen-buying interventions — challenging the yen's prolonged weakness amid a widening RBA-BOJ policy rate gap,

How the BOJ's hawkish shift is challenging yen weakness

• Rate hikes to a 30-year high (1.00%). The BOJ raised rates to 0.75% in December 2025 and then to 1.00% by June 2026, marking a historic normalization . It has signaled that further hikes are coming, with a Reuters poll showing a majority of economists expect another hike by December and possibly as soon as October .
• "Core inflation could exceed target" warning. At its July 30–31 meeting, the BOJ warned for the first time that underlying inflation could exceed its 2% target, and said future policy discussions would focus on upside price risks — a distinctly hawkish tone .
• Coordinated yen-buying interventions. Japan's Ministry of Finance conducted multiple large interventions:
  • ~$59–73 billion in coordinated action with the US in late April–May 2026, which temporarily pulled AUD/JPY back from its highs .
  • Another intervention in late July 2026 alongside the BOJ's hawkish rate-hold decision, though it failed to give the yen lasting support .
• Persistent yen pressure. Despite these efforts, the yen remains near 40-year lows against the USD (~160) and continues to weaken on the crosses, as the underlying rate differential dwarfs the impact of one-off intervention .

The risk from softer Australian inflation

• Australia's Q2 2026 inflation undershot forecasts. The trimmed mean CPI came in at 3.6% (below expectations), and June headline CPI eased to 3.8% YoY from 4.0% .
• Rate hike bets have been slashed. Markets now see little chance of an RBA hike in August 2026, and the probability of any 2026 hike fell to about 50% .
• Near-term AUD/JPY pullback. AUD/JPY dropped ~0.65% on the inflation miss, falling to around 113.60 as traders repriced RBA expectations . The Commonwealth Bank now says the RBA is likely on hold for the rest of 2026 .
• Key caveat: The RBA's cash rate is still 4.35–4.60%, and markets see virtually no chance of a cut this year . As long as the rate gap with Japan remains 300+ bps, the structural carry-trade bid likely persists even if near-term RBA tightening expectations fade.

Summary assessment

The AUD/JPY surge is fundamentally a story of divergent monetary policy — the RBA is still in tightening/hold mode while the BOJ, despite its hawkish pivot, is normalizing from near-zero. The ~350 bps rate gap has revived yen-funded carry trades that keep the pair elevated. Japan's interventions and the BOJ's hawkish rhetoric have caused temporary pullbacks but have not reversed the trend, because the fundamental rate differential remains intact. The latest soft Australian inflation data has taken some upside pressure off AUD/JPY by reducing RBA hike bets, but as long as the RBA holds rates well above the BOJ, the pair's multi-decade-high bias is likely to persist until either the BOJ tightens much more aggressively or the RBA cuts.