After 2014 set the record for annual average global surface temperature, 2015 promptly smashed it. By the end of 2015, the incredibly strong El Niño that had developed to help fuel that record enabled climate scientists to predict that 2016 was almost certain to break the record again. With the first half of 2016’s temperatures in the books, this prediction is proving to be on target.

In a press conference Tuesday, NASA scientists highlighted the standout temperatures we've seen so far in 2016. This has been, far and away, the warmest January-to-June period on record.

Even though the El Niño event has now come to an end, with forecasts pointing to cooler La Niña waters in the eastern equatorial Pacific Ocean, 2016 is a virtual lock to be significantly warmer than 2015. This June also set the record for the warmest temperature on record in June—the 8th straight month that this has happened.

The early expectation for 2017, however, is that the developing neutral or La Niña conditions will put an end to the streak of record years.

The El Niño/La Niña see-saw is a an important factor in the year-to-year variability of global temperature, but it's obviously taking place on top of the long-term warming trend driven by human activities. Every year, an El Niño is capable of pushing average global temperatures a little higher than it could the year before. NASA’s Gavin Schmidt estimated that only about 40 percent of 2016’s increase over 2015 can be blamed on El Niño conditions.

Meanwhile, Arctic sea ice is also having an interesting year. The extent of Arctic sea ice has been at or near a record low all year long. That's due to weather—warm temperatures (especially an early start to the melt season) and winds conducive to dispersing the ice pack. So will 2016 break 2012’s record for the lowest Arctic sea ice extent at the end of the melt season in September?

NASA’s Walt Meier cautioned that while it’s certainly likely to be low—also following the longer-term trend—we have a couple months of weather yet that will determine the final result. “The first six months certainly have primed things to potentially be a record, but the summer melt season [from June to August] is really crucial. It really depends a lot on what happens there,” Meier said.