It was so hot that the candles melted completely
Having no air conditioning can be hard to deal with during the summer months, especially in regions that have tropical weather. The heat will not necessarily kill you, but it will make you feel very uncomfortable and even cause some people to faint. It can also cause your candles to melt, apparently.
Nevertheless, it takes quite a bit of heat to melt the wax. We suspect the cause for these candles falling over must not have been that it was hot outside, but that they were left too close to a stove or a heater. In general, houses do not get hot enough for this to happen.