3-year trends to April 2020

April, like March, continued cool

April raw anomaly data (orange)

Current raw anomaly values for April appeared very little changed from those of March. However, as noted below, many values are estimates only.


Daily maximum temperature anomaly (all x-axes), which had been very high until January, remained near -1.5°.
Daily minimum temperature anomaly (lower left): stayed just below normal.
Subsoil temperature anomaly (lower right): stayed near normal.

Moistures (moist is at the bottom)

Rainfall anomaly (upper left) stayed near normal.
Cloudiness anomaly (upper right): fell from very high to high.
Dew point anomaly (middle left): remained normal.
Daily temperature range anomaly (middle right) stayed near -1.5°.

 Fully smoothed data values (red) 

The fully-smoothed daily maximum temperature anomaly for October 2019 again broke the 21st century record, reaching a value of 2.21° above normal. The daily minimum anomaly also rose, but the subsoil anomaly fell. Despite the high and increasing air temperatures, smoothed moisture anomalies for October 2019 did not move further towards drought.

Due to illness, 45 days were missed for some Manilla values for the whole of April 2020. No values were noted for cloud or soil temperature; daily maximum and minimum air temperatures were estimated by regression on values from Tamworth Airport Automatic Weather Service.]


January data points are marked by squares.

Smoothing Continue reading

3-year trends to April 2019

April no rain

3-year trends to April 2019

April raw anomaly data (orange)

In April 2019, a rainfall total of zero made the raw anomaly for rainfall minus 40 mm. Rainfall, and the other moisture indicators (cloudiness, dew point, and daily temperature range) were much further up the graphs towards drought than they had been in March.
Daily maximum, minimum and subsoil temperatures were high, near the high-side limits of (smoothed) normal temperature.

 Fully smoothed data (red)

Fully smoothed data to October 2018 show rainfall just short of the record negative anomaly set in May 2018, and both maximum and minimum temperatures near record positive anomalies. However, cloudiness, dew point, and daily temperature range continued a movement (down) away from drought.


January data points are marked by squares.


Smoothing uses Gaussian functions.
For fully smoothed data the function has a Standard Deviation of 2.5 months, it spans 13 monthly data points, and has a half-width of 6 months, which suppresses cycles shorter than 12 months. For partly smoothed data, the span of the function is reduced to 11 months, 9 months and so on.
Continue reading

April 2018 very warm and sunny

Gum tree

Schoolyard Lemon-scented Gum

Warm spells several degrees above normal persisted until late in the month. Then normal temperature returned.
While no day went over 35°, thirteen days went over 30°, which was a record. ANZAC Day, at 27.3°, was 3° warmer than usual. That was much the same as last year, but not nearly as warm as in 2002 (28.7°).
A record 25 nights were warmer than 10°. There were no frosts, the coldest night (the 29th) being 5.2°.
There were only three rain days, with the highest reading of 10.2 mm on the 20th. The number of cloudless mornings (16) was a new record, beating April 2001 (15).

Weather log for April 2018

Comparing April months

As in March, so in April, this very warm dry month matched the same month in 2016. The three highest mean temperatures for April months were: in 2018, 20.7°; in 2005, 20.6°; and in 2016, 20.5°. For mean daily maximum temperatures, however, 2005 was the warmest, at 29.5°. April 2018 claims the record highest mean minimum temperature of 12.5°, beating April 2014, which had 12.2°.
The rainfall total of 17.8 mm was at the 31st percentile, well below the average (40 mm). In 2018, rainfall has been below normal in January, March and April. However, serious rainfall shortages below the 10th percentile are still seen only in the medium term: the 60-month total of 2780 mm is at the 8th percentile, and the 72-month total of 3370 mm is at the 6th percentile.

Climate in April months

Data. A Bureau of Meteorology automatic rain gauge operates in the museum yard. From 17 March 2017, 9 am daily readings are published as Manilla Museum, Station 55312.  These reports use that rainfall data when it is available.  The gauge, which had last reported on 24 September 2017, came on line again on the 16th of March.

All data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to April 2018

Hot and sunny

3-year trends to April 2018

April raw anomaly data (orange)

Raw temperature anomaly values for April 2018 were very high for daily maxima, daily minima and subsoil. Rather low moisture was shown by the rainfall and daily temperature range anomalies, while cloudiness was very low (sunny days), but dew point was near normal.

 Fully smoothed data (red)

In the latest fully-smoothed data, for October 2017, while rainfall anomaly continued to move up its graph towards dryness, the other three moisture anomalies (cloudy days, dew point, and daily temperature range) had just begun to move down towards wetness.
For temperatures, both daily maximum anomaly and daily minimum anomaly were rising rapidly. Subsoil temperature anomaly continued the rapid fall from its peak value (normal) in June 2017.


Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

 * Normal values for rainfall are based on averages for the 125 years beginning 1883.

Cool Dry April 2017

Pavonia blooms on a roadside

Roadside Pavonia

April began with cool days and nights, about three degrees below normal. However, the weather did not get any cooler until the last few days. In particular, ANZAC Day, at 27.4°, was the warmest day of the month – but that was more than a degree cooler than ANZAC Day 2002. (The average daily maximum temperature for ANZAC Day (from 2000) is 24.3°. The hottest was 28.7° (2002) and the coldest 16.8° (2012).)

Soaking rain of 10.6 mm, registered on the 26th, came with a remarkably warm night of 16.6°. Coming so late in autumn, this was 7.9° above normal, breaking the record of 7.1° above normal for an April night (20/04/06).
Further rain on the 27th (11.2 mm) fell as showers on a very cold day of 14.3°, that was 9.8° below normal. The final three nights were cold. The 30th, at 4.3°, was the coldest night of the month, but it was far from frosty.

Weather log for April 2017

Comparing April months

This month was cool, with a mean temperature of 17.0°, but not nearly as cool as April in 2008 (15.8°), 2006 (16.6°), or 1999 (15.6°). It was also rather low in moisture, with only 24 mm of rain, only 33% cloudy mornings, a daily temperature range as wide as 15.6°, and an early morning dew point of only 6.3°. What is unusual is the combination of low temperature values and low moisture values. Manilla’s climate generally swings between high temperature with low moisture (“droughts”) and low temperature with high moisture (“flooding rains”), as the poet said. (See these graphs.)
The total rainfall of 24.0 mm was at the 40th percentile, below the April average of 40 mm. There are no serious shortages of rainfall for groups of months to this date.

Climate for April 2017.

Data. A Bureau of Meteorology automatic rain gauge operates in the museum yard. From 17 March 2017, 9 am daily readings are published as Manilla Museum, Station 55312.  These reports use that rainfall data when it is available. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.