Monthly Seasonality Overlay
Seasonality is usually checked by pulling up a separate spreadsheet of past monthly returns. This indicator puts the same number directly on the chart: every bar shows the average return its own calendar month has produced across every complete year in the loaded history, so a trader looking at a March bar sees the historical average March return without leaving the chart. Each calendar month's return is measured once per year, from that month's first bar open to its last bar close, and the resulting yearly samples for a given month (all the past Marches, for example) are averaged into a single number. There is deliberately no minimum sample count that hides a month with little history - instead the on-chart label states the sample size plainly (for example "n=3 years"), so a thin sample is visible as thin rather than silently presented with the same confidence as a twenty-year average. The histogram is a slow-moving statistic - averaged across years, it does not change meaningfully tick to tick - so it is only rebuilt every InpRebuildEveryBars new bars rather than on every recalculation, keeping the indicator cheap even on long history. Notes and limitations - This is a descriptive statistic over past years, not a prediction - a positive historical average for a month is not a signal that the current occurrence of that month will also be positive. - Depends entirely on how much history the terminal has loaded; a freshly opened chart with only a few months of history will show a thin or empty seasonal curve until more data is downloaded. - The current, still-forming month is included as a partial sample once it has at least one bar, so the count for the current month can include an incomplete year alongside complete ones. - Each month's return uses that month's own first-bar open and last-bar close from the chart's native timeframe; it does not fetch a separate Monthly time series internally.
Indicator · MT5 · v1.0 · Free
About Monthly Seasonality Overlay
Monthly Seasonality Overlay is an indicator for MetaTrader 5. It has 2 settings, such as Lookback years and Rebuild every bars. MQL source code included.
Files in the download: Seasonality.ex5, Seasonality.mq5, Seasonality.txt.
Settings
| Setting | Default | What it does |
|---|---|---|
| Lookback years | 15 | Years of history averaged into the seasonal curve (0 = use everything loaded) |
| Rebuild every bars | 20 | Recompute the average every N new bars, not every bar |
How to install
- Download the ZIP from your PolyMaria library and unzip it.
- In MetaTrader 5 open File → Open Data Folder, then go to MQL5 → Indicators.
- Copy the .mq5 file(s) there. Put any .mqh files in MQL5 → Include.
- Open the .mq5 file in MetaEditor and press Compile (F7) if MetaTrader does not show it.
- Drag the indicator from the Navigator onto a chart and adjust the settings.
Tags: MT5 Indicator · MQL5 Source Code