Adelaide is entering its fourth hot spell for the month which will ensure this December is the hottest in 129 years of records. The average temperature will come in above 25 degrees (combining nights and days), more than three-and-a-half degrees warmer than the long-term norm. This is a half-a-degree hotter than the previous December record, set in 1897. This December is even about two degrees hotter than the average January and February, typically the hottest summer months. With the city reaching the low thirties today and mid-to-high thirties on the last three days of the month, daytime maximum temperatures will end up averaging about 32.5 degrees for the month. This is more than five degrees hotter than average. The city is a chance of reaching 40 degrees on New Years Eve. If it does this would be the seventh 40-degree day this month, beating the previous December record by three days and making this December the hottest on record. And to rub it in, Adelaide may be the hottest capital at midnight on New Year's Eve. The effects of the heat have been compounded by a dry past three months when only 32mm fell, well short of the 100mm average. This has been the driest end to a year since 1982 when 27mm fell in the last three months. Gardens, parks, paddocks and trees have dried out markedly and dam levels are dropping. The Adelaide catchment has dropped below 35 percent capacity. This time last year it was still above 70 percent. The drying out cannot just be blamed on the last few months, the year as a whole is more than 150mm short of the annual average rainfall of 549mm. The year 2015 will end up being the driest year since 2006. Looking ahead, the rain prospects are not good for the next week-or-so despite it cooling down a bit.