Forex Monthly and Weekly Seasonality

Forex has no earnings season and no dividend calendar — but it has seasonality. It just hides in fiscal year-ends, repatriation flows, and month-end rebalancing rather than in corporate calendars. Learn the schedule and you trade alongside the flows, not against them.

Currency seasonality is driven less by traders' calendars and more by the institutional and corporate flows that move through specific dates.

Monthly seasonal patterns

Documented monthly tendencies (vary by year, regime, and rate cycle):

Pair / currency	Notable seasonal tendency
USD	Strength into year-end; funding pressure spikes
JPY	Repatriation into March 31 (Japanese fiscal year-end)
GBP	Spring strength historically ("sell in May" inverse)
AUD	Commodity-linked; tied to metals and China demand
CAD	Energy-linked; tracks oil seasonal demand

These are tendencies, not laws. They reverse when rate differentials or risk sentiment override them.

The March 31 effect (Japan)

Japan's fiscal year ends March 31, the largest repatriation event in FX. Japanese institutions and corporations convert foreign assets back to yen to dress balance sheets for the new year. This historically biases JPY strength into late March.

March 31 is the single most reliable calendar event in FX. Watch for JPY demand building in the back half of March, and expect thinner, driftier markets in early April.

Month-end rebalancing

Pension funds, sovereign funds, and model portfolios rebalance at month-end. The largest flow hits the last few trading days, when firms adjust FX hedges to match equity/bond weights. The result: predictable month-end flow in the majors, often a USD bid or offer depending on prior-month asset moves.

Half-year and year-end

• June 30: half-year portfolio dressing, mid-year reporting
• December 31: full-year dressing, tax-loss/realization, USD funding stress

These dates concentrate flow and can produce sharp moves — particularly in cross-currency basis swaps, where USD funding demand spikes.

Weekly patterns

• Monday/Tuesday: trends often begin; flows from weekend news are absorbed
• Wednesday–Friday: existing trends extend or fade
• Friday: position-squaring into the weekend; gap risk priced into options

The "weekend gap" effect: currency pairs gap on Sunday/Monday open more often than chance, reflecting news accumulated while markets were closed.

What drives it all

Driver	When
Fiscal year-ends	March (Japan), June (some), December (most)
Month-end rebalancing	Last 3–4 trading days
Quarter-end	March, June, Sept, Dec
Corporate repatriation	Around fiscal year-ends
Option expiry	NY cut, 10am, monthly roll

How to use FX seasonality

1. Mark March 31, June 30, December 31 on your calendar — they bias JPY and USD
2. Watch month-end for rebalancing flows in the majors
3. Combine with rate differential: seasonality is strongest when it aligns with the carry
4. Don't fight the fiscal year-end without a strong fundamental reason
5. Trade flow, not folklore: the date matters; the "why" confirms it

Caveats

• FX is noisy; sample sizes are smaller than equities
• Regime matters: a rate-hiking USD ignores most seasonal tendencies
• Central bank intervention can override any calendar

Practical steps

1. Add fiscal year-ends and quarter-ends to your trading calendar
2. Watch USD funding stress indicators (cross-currency basis) into year-end
3. Expect JPY strength building into late March
4. Note month-end rebalancing flow in the last 3 sessions
5. Combine seasonal bias with carry and trend — confluence beats calendar alone

Bottom line

FX seasonality is flow seasonality. The dates are real, the flows are predictable, and trading with them beats trading against them — when carry and trend agree.