Temperature Update - April 2018, UAH

Roy Spencer announced the April update for UAH Global Temperature, and it continues the theme of being not too interesting.

According to the UAH satellite data, April was 0.21°C above the 1981-2010 base period. This compares with 0.24°C last month. This makes 2018 the 7th warmest April since the start date of 1979.

The trend over the entire data set for the months of April is slightly less than the trend for all months at 1.17°C / century. Or if you prefer, Tony Heller would argue there has been no trend in April temperatures in 20 years.

Looking at all months the trend continues at 1.28°C / century, substantially slower than all other data sets, with this month again being just below the trend.

Predictions

The mid-point prediction remains unchanged from last month, but with slightly better confidence. My prediction, based purely on simple statistical analysis is that 2018 will be 0.243 ± 0.117°C. This compares with last month's prediction of 0.243 ± 0.136°C.

The current average for the first four months is 0.228°C, so the prediction requires temperatures to rise slightly over the rest of the year. This is simply because so far 2018 has been below the trend line and there is an expectation that it is more likely temperatures will move towards the trend.

As far as rankings are concerned, 2018 is most likely (~60%) to finish either 5th or 6th warmest, but more likely to finish below 6th, than above 5th. There's a small chance (~5%) that 2018 will finish 4th or 3rd, and virtually no chance of finishing 2nd. There's about a 1 in 3 chance it could finish below 6th place, in which case it could easily finish anywhere done to 12th place and possibly lower.

Here are the probabilities for each ranking down to 12th.

UAH 6.0 Probabilities - Based on Data up to April 2018

Rank	Year	Anomaly	Probability	Cumulative
1	2016	0.51	0.00%	0.00%
2	1998	0.48	0.01%	0.01%
3	2017	0.38	1.43%	1.44%
4	2010	0.34	4.48%	5.92%
5	2015	0.27	29.11%	35.03%
6	2002	0.22	32.69%	67.72%
7	2005	0.2	9.87%	77.59%
8	2003	0.19	5.81%	83.40%
9	2014	0.18	3.25%	86.65%
10	2007	0.16	5.69%	92.35%
11	2013	0.13	4.33%	96.68%
12	2001	0.12	1.65%	98.32%
Below 12	n/a	n/a	1.68%	100.00%