Why the Moon Matters
Jones placed significant weight on lunar cycles for moisture prediction. His reasoning was layered. The Moon's gravitational pull affects ocean tides. Atmospheric tides are real, measurable pressure variations, though much smaller in magnitude. And the Moon's phase shows a correlation wiht changes in atmospheric pressure patterns. That correlation is documented, though the mechanism is still poorly understood.
I'll be direct about where I stand on this. The correlation is not perfect. It's a tendency. But across hundreds of months of Queensland weather data, the tendency shows up often enough to be worth tracking. On this moment we have 21 years of Dayboro records alongside the historical Queensland data, and the lunar signal is there. Not every month. Not every year. But statistically it's not noise.
This is the most contested part of the Jones method. Some researchers working wiht the same data find the signal; others don't. The difference usually comes down to methodology and the length of the record. Short records miss it. I include the moisture chart because it adds information to the forecast. Not because it's certain. If you're uncomfortable wiht that level of uncertainty, this part of the method isn't going to satisfy you.
The Four Phases and What They Tend to Signal
A complete lunar cycle (New Moon to New Moon) is 29.53 days, the synodic month. Each cycle divides into four roughly equal phases of about 7.4 days each. Jones built his moisture chart around these four periods.
| Phase period | Duration (approx.) | Tendency for Dayboro | Weighting |
|---|---|---|---|
| New Moon (New Moon to First Quarter) | ~7.4 days | Slight tendency toward increased storm activity and rainfall, particularly in summer. Pattern appears in Queensland BoM records. | Full weight |
| First Quarter (First Quarter to Full Moon) | ~7.4 days | Transition. Least reliable signal in our records. Variable outcomes. | 50% of New/Full Moon reading |
| Full Moon (Full Moon to Last Quarter) | ~7.4 days | Slight tendency toward higher pressure and drier conditions, particularly in winter and autumn. | Full weight |
| Last Quarter (Last Quarter to next New Moon) | ~7.4 days | Transition. Slightly stronger signal than First Quarter in our records, but still weaker than New/Full phases. | 60% of New/Full Moon reading |
The New Moon and Full Moon periods carry the most signal. The First Quarter is the weakest. That's what our Dayboro records show. Your location may differ slightly, which is another reason to build your own dataset rather than just borrowing ours.
Getting the Timing Right
Use AEST (Australian Eastern Standard Time, UTC+10) for all lunar phase times. Queensland does not observe daylight saving, which simplifies things. You don't need to adjust for summer versus winter.
A Full Moon at 01:30 AEST is just after midnight, the early hours of that calendar day. A New Moon at 23:00 AEST is 11 pm, the same calendar day. This matters because the rainfall tendency doesn't switch exactly at the moment of the phase. The signal shows up across a window of roughly 12 to 48 hours around the phase time. So a New Moon at 23:00 AEST on a Monday means the increased moisture tendency covers Sunday night through Tuesday or Wednesday.
Download phase times from the USNO (US Naval Observatory) at aa.usno.navy.mil/data/MoonPhases wiht the timezone set to UTC+10. The USNO tables go forward several years and are accurate to the minute. They're free and there's no reason to use anything else.
Print the full year's phase table before you start building the chart. Trying to look up individual phases as you go is slower and you'll make timing errors.
Building the Moisture Chart
Create a column for every month in your forecast period. Twelve columns for a full year forecast, or fewer if you're building incrementally.
For each month, list the dates and times of all four lunar phases. Then build the comparison. Find all years in your historical record where the same lunar phase fell in the same general calendar week, under similar cycle conditions. By "similar conditions" I mean: same phase of the Schwabe sunspot cycle (within 1 or 2 years), similar Jupiter and Saturn positions (within about 5 degrees).
Note the actual Dayboro rainfall recorded in those comparison years during each phase period. Average those values. Express the result as a tendency: wetter than average, drier than average, or no clear signal. Getting no signal is common and is a legitimate forecast result. Don't force a reading where there isn't one.
Handling sparse data
Some lunar phase and sunspot cycle combinations don't have many historical matches. A 35-year sunspot cycle (the Brückner cycle, covered more in Step 6) means some configurations only recur 2 or 3 times in your entire record. That's not enough for statistical confidence. In those cases, widen the tolerance on your matching criteria, accept a weaker analogue, and note the uncertainty explicitly in your forecast.
We have about 120 years of Queensland rainfall records to draw on, plus the Dayboro specific data from 2004. The Queensland records are essential for phases that the Dayboro dataset alone can't populate.
An Example from Our Records
For May 2025, the New Moon fell on 27 April (AEST). We looked at past New Moon occurrences in late April under Schwabe cycle decline conditions, which is what we were experiencing at the time. Jupiter was actually in a similar longitude range (Gemini) in 1989, 2001, and 2024. Average Dayboro rainfall in the first week of May in those years was 38mm.
The historical May average for Dayboro runs about 93mm for the full month, so roughly 23mm per week on average. A reading of 38mm for that first week suggested a slightly wetter than average moisture tendency for the period 27 April to 4 May. That's the process. Work out what the analogues show. Compare wiht the historical average. Express as a tendency.
The actual outcome for that week was 41mm. That's not a vindication of the method across one data point. But it illustrates how the chart is used and what a wetter than average moisture tendency means in practice.
What the Moisture Chart Does Not Tell You
I've seen people take the moisture chart and try to pinpoint a rain day from it. That's not what it does. A high moisture tendency week wiht a New Moon in late November means the week as a whole is more likely than average to record wetter than average rainfall. It does not mean Tuesday specifically will have a storm. That precision requires different tools entirely.
Once the moisture chart is built, you have all three charts: temperature, air movement, and moisture. Step 6 explains how to find the pattern matches in the historical record that translate these charts into an actual forecast tendency for a specific period. If you're using the moisture tendency primarily for planting decisions, the seasonal guides at Garden Buddy are built around the same climate zones and work alongside a monthly outlook rather than replacing it.