It is that time of the year when the skies are blue and everything is very dry. Timber floors are a hygroscopic material, (they gain or lose moisture) and they react to these dry times and gaps start to appear. These gaps can appear quite suddenly and may continue to widen as the floor acclimatises itself to the current conditions.
It is all about the humidity, which can get very low at this time of year. As the air dries, the moisture in the timber leaves, which then shrinks and gaps appear. This can happen quite quickly, particularly if there is a strong breeze around. This, however, is all quite normal and should not be a cause for concern. You might also see similar behaviours if air conditioning is used extensively to warm or dry the room, or near glass that has direct sunlight and therefore excessive heat.
So, what do you need to do? Well, when the climatic conditions change and the rains come, your floor will absorb moisture and expand and the gaps will disappear. So, unless you are particularly concerned about how your floor looks, there is nothing you need to do.
If you are concerned, there are some things you can do to reduce the gapping. You should have your house ventilated when the humidity is highest and the breezes are lowest, so that means early morning, evening and over-night, avoid the afternoons and middle of the day. Draw your curtains in the middle of the day and/or have your windows tinted. You can also leave water in the sink, or a mobile clothes line with some damp clothes hanging overnight.
Otherwise, continue to enjoy your timber floor and know that the character of your floor is part of its appeal!