My method for obtaining this result was as follows.

1. On request from the Australian Bureau of Meteorology (www.bom.gov.au) I obtained a data file for daily rain records at Observatory Hill near the Sydney Harbour Bridge from 1 January 1980 to 22 May 2007, 10003 days. I put this in an excel spreadsheet (column A).
2. In excel, I have a digital planetary ephemeris which enables easy creation of lists of planetary angles seen from earth over any period, including with sun and moon. In this spreadsheet each point of the zodiac cycle has a defined number from 1 to 13 with 1 the northern vernal equinox (Sun March 21), 4 the northern summer solstice, 7 the fall equinox and 10 the winter solstice, etc. I combined these two spreadsheets, and then, for each pair, eg Moon (B) and Uranus (C), extracted the rain records data for each day of the roughly 29 day monthly cycle. (Uranus orbit of 84 years is so slow that it barely moves each month).
3. A column (D = B - C) gives the difference between the positions of Moon and Uranus on each day. Minus six is opposition, zero is conjunction and plus six is opposition. For the sun-moon cycle, full moon is indicated by plus or minus six, half moon is plus or minus three, and new moon is zero. Difference numbers outside the -6 to 6 band are corrected by adding or subtracting 12.
4. Next step makes 29 columns in the spreadsheet dividing the numbers between -6 and 6 into even amounts, with increment 12/29 = ~0.41. The formula used in these columns is =AND($H3>=I$1,$H3<=I$2), where $H3 is the Moon Uranus difference (eg -5.8), I$1 is the lower bound (eg -6) and I$2 is the upper bound for that day (eg -5.59 for the first day after opposition). This formula returns TRUE for hits and FALSE for misses.
5. Next step is a further 29 columns with the formula =IF(I3=TRUE,$E3,0), where $E3 is the rain recorded in millimeters on that day and I3 is the result from step 4. This converts TRUE to the actual rain record in millimeters, and FALSE to zero The totals of each of these columns are the cumulated millimetres of rain for each day of the Moon-Uranus cycle in the 27 year period. Results are as follows for each day beginning from the opposition: 986.50; 1070.20; 1172.20; 1172.60; 1787.00; 1215.20; 1130.40; 1121.60; 1407.00; 971.90; 561.80; 1089.00; 892.60; 1137.80; 1281.20; 1122.80; 1081.00; 1257.00; 1130.90; 1363.00; 1082.60; 1164.90; 940.40; 1020.20; 1454.80; 1117.00; 1115.70; 1280.60; 1004.80
6. These 29 results have average of 1142.5 and standard deviation of 210.1283. Result 5 (1787mm ten days before conjunction) is most anomalous, 3.07 standard deviations above average. This result contains the rainiest single day, 6 August 1986, when 327.6 mm were recorded, but this single result accounts for less than half of the difference from the average. The other spike is result 11 (561.8mm). Five of the 29 results are more than one standard deviation from average.
7. All the obtained results showing the most anomalous results comparing planet-moon cycles against rain levels with the same data and method were as follows:
Test: Moon Planet Rain Cycle for Sydney 1980-2007 Minimum Result Maximum Result Ratio Max/Min Difference
Uranus-Moon Rain mm 561.80 1787.00 3.2 1225.20
Venus-Moon Rain mm 819.60 1663.20 2.0 843.60
Jupiter-Moon Rain mm 712.60 1508.60 2.1 796.00
Sun-Moon Rain mm 850.00 1620.80 1.9 770.80
Neptune-Moon Rain mm 729.20 1450.80 2.0 721.60
Saturn-Moon Rain mm 790.60 1386.80 1.8 596.20
Mars-Moon Rain mm 915.00 1401.20 1.5 486.20
Uranus Standard Deviations from average -2.76 3.07 5.83
Venus Standard Deviations from average -1.74 2.81 4.55
Neptune Standard Deviations from average -2.37 1.77 4.14
Sun Standard Deviations from average -1.46 2.39 3.84
Saturn Standard Deviations from average -2.13 1.48 3.62
Jupiter Standard Deviations from average -1.89 1.61 3.50
Mars Standard Deviations from average -1.59 1.81 3.40
8. Other results from this dataset involve counting the number of days of rain, light rain (<10mm) and heavy rain (>10mm) for each lunar-planetary combination and analyzing binomial distributions.