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Real-time SOI Data

Numerical data from here and values are calculated using the 1887-1989 base period. This information is usually updated every weekday at 2:00pm (AEST), public holidays excluded.

Date Pressure at Tahiti (hPa) Pressure at Darwin (hPa) Daily value 30-day average SOI 90-day average SOI
1-Dec-2020 1014.91 1007.10 21.23 (-6.95) 8.99 (-0.25) 7.70 (+0.01)
30-Nov-2020 1013.51 1006.20 28.18 (+8.78) 9.24 (+0.26) 7.69 (+0.11)
29-Nov-2020 1012.23 1006.30 19.40 (+18.19) 8.98 (+0.64) 7.58 (-0.02)
28-Nov-2020 1010.77 1007.70 1.21 (-1.97) 8.34 (+0.50) 7.60 (-0.24)
27-Nov-2020 1010.13 1006.75 3.18 (-2.03) 7.84 (+0.59) 7.84 (-0.17)
26-Nov-2020 1009.30 1005.60 5.21 (-0.45) 7.25 (+0.29) 8.01 (-0.05)
25-Nov-2020 1009.77 1006.00 5.66 (+2.74) 6.96 (+0.28) 8.06 (+0.07)
24-Nov-2020 1010.69 1007.35 2.92 (+10.75) 6.68 (+0.32) 7.99 (+0.10)
23-Nov-2020 1010.25 1008.60 -7.83 (-0.32) 6.36 (-0.3) 7.89 (-0.05)
22-Nov-2020 1010.60 1008.90 -7.51 (-10.37) 6.66 (-0.55) 7.94 (-0.21)
21-Nov-2020 1011.63 1008.30 2.86 (-14) 7.21 (-0.23) 8.15 (-0.08)
20-Nov-2020 1013.38 1007.85 16.86 (-3.31) 7.44 (+0.45) 8.23 (+0.09)
19-Nov-2020 1014.15 1008.10 20.17 (+0.07) 6.99 (+0.72) 8.14 (-0.04)
18-Nov-2020 1014.69 1008.65 20.10 (+2.41) 6.27 (+0.89) 8.18 (-0.07)
17-Nov-2020 1014.71 1009.05 17.69 (+6.24) 5.38 (+0.85) 8.25 (-0.12)
16-Nov-2020 1014.73 1010.05 11.45 (+1.53) 4.53 (+0.70) 8.37 (+0.01)
15-Nov-2020 1014.74 1010.30 9.92 (-7.77) 3.83 (+0.54) 8.36 (+0.15)
14-Nov-2020 1014.21 1008.55 17.69 (+6.43) 3.29 (+0.83) 8.21 (+0.21)
13-Nov-2020 1014.20 1009.55 11.26 (+4.52) 2.46 (+0.45) 8.00 (+0.07)
12-Nov-2020 1014.64 1010.70 6.74 (+0.38) 2.01 (-0.12) 7.93 (+0.05)
11-Nov-2020 1014.73 1010.85 6.36 (+2.74) 2.13 (-0.16) 7.88 (+0.14)
10-Nov-2020 1013.35 1009.90 3.62 (+1.14) 2.29 (-0.28) 7.74 (+0.14)
9-Nov-2020 1012.67 1009.40 2.48 (-10.88) 2.57 (-0.39) 7.60 (-0.07)
8-Nov-2020 1014.23 1009.25 13.36 (+6.75) 2.96 (-0.21) 7.67 (+/-0.00)
7-Nov-2020 1014.72 1010.80 6.61 (+11.32) 3.17 (-0.24) 7.67 (-0.03)
6-Nov-2020 1013.29 1011.15 -4.71 (+1.08) 3.41 (-0.63) 7.70 (-0.14)
5-Nov-2020 1013.57 1011.60 -5.79 (-9.16) 4.04 (-0.62) 7.84 (-0.32)
4-Nov-2020 1015.26 1011.85 3.37 (-11.39) 4.66 (-0.22) 8.16 (-0.25)
3-Nov-2020 1016.75 1011.55 14.76 (-8.59) 4.88 (+0.26) 8.41 (+0.02)
2-Nov-2020 1017.05 1010.50 23.35 4.62 8.39




Charts: 2020 | 2019 | 2018 | 2017 | 2016 | Source: The State of Queensland, Australia

ENSO Wrap Up (Source: here)

Issued on 24 November 2020


La Niña continues in the tropical Pacific. International climate models suggest it is likely to continue to at least February 2021.

Central and eastern tropical Pacific Ocean sea surface temperatures (SSTs) are at La Niña levels. Models suggest the current La Niña will strengthen further, peaking in December 2020 or January 2021 at moderate to strong levels.

Most oceanic and atmospheric indicators reflect a mature La Niña. Recent variability in the Southern Oscillation Index have been related to the Madden–Julian Oscillation (MJO), rather than the state of the La Niña.

The Southern Annular Mode (SAM) is neutral but is expected to increase to positive values over the coming week. This is driven in part by the La Niña influence, and in part by a stronger than average polar vortex over Antarctica. Positive values are expected at least into early 2021, and typically increase rainfall in south eastern Australia.

The Madden–Julian Oscillation (MJO) is at weak to moderate strength, having moved from the Atlantic to the eastern Indian Ocean in November. This pattern tends to be unfavorable for rain in Australia. The MJO is expected to weaken as it moves over Indonesian longitudes, though may bring increased rainfall over parts of northern Australia and be favourable for monsoon onset when it moves past the Top End.

Climate change is also influencing the Australian climate. Rainfall across northern Australia during its wet season (October–April) has increased since the late 1990's, with a greater proportion of high intensity short duration rainfall events.

Climate outlooks indicate December 2020 to February 2021 rainfall is likely to be above average for most of the country. Current La Niña conditions, though not as strong as 2010–12, warmer than average waters to the north of Australia, climate change and a positive SAM are contributing to the increased chances of rainfall over Australia. The state of the Indian Ocean is not as conducive to increased rainfall as it was during 2010–12.


SOI summary:

The 30-day Southern Oscillation Index (SOI) for the 30 days ending 22 November was +5.7. The SOI has returned to values more consistent with La Niña. The earlier dip in 30-day SOI values followed the passage of the Madden-Julian Oscillation (MJO) through the Maritime Continent earlier in the 30-day period. The 90-day SOI value was +7.9.

Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña. Values between +7 and −7 generally indicate neutral conditions.


Sea surface temperature summary:

The sea surface temperature (SST) map for the tropical Pacific Ocean for the week ending 22 November shows cool anomalies extending across the tropical Pacific, covering areas east of 160°E and to the south of the equator in the eastern Pacific. The strength of these cool SST anomalies remains similar to that of last fortnight. Warm anomalies remain in the Maritime Continent and waters close to much of northern, eastern, and south-western Australia.

The latest values of the three NINO indices in the tropical Pacific for the week ending 22 November were: NINO3 −0.9 °C, NINO3.4 −1.0 °C, NINO4 −0.4 °C. NINO3 has cooled further compared to two weeks ago, while NINO3.4 and NINO4 have weakened slightly.

Persistent NINO3 or NINO3.4 values warmer than +0.8 °C are typical of El Niño, while persistent values cooler than −0.8 °C typically indicate La Niña.


ENSO outlooks:

All international climate models surveyed by the Bureau indicate the current La Niña will likely persist until at least February 2021. Most climate models reach their peak in December, with some peaking in January. Six of eight models indicate thresholds will still be met in March, although all six show central Pacific sea surface temperatures much declined from their summer peak.

While some models indicate that the current La Niña could possibly reach similar strength to the La Niña of 2010–12, La Niña conditions are currently weaker than at the same point in 2010. Sea surface temperatures in the central and eastern tropical Pacific are the coolest since the end of the La Niña event in 2012, but they are not as cool as during spring or early summer 2010.

La Niña increases the likelihood of above average rainfall across much of Australia during spring, and across much of eastern Australia during summer. La Niña increases the chance of cooler than average daytime temperatures for large areas. It also increases the chance of tropical cyclones, and earlier first rains of the northern wet season.

Last Accessed: Tue Dec 01 2020 13:29:17 HKT
Last Modified: Wed Jul 24 2019

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