Being a tropical country, Indonesia does not have spring, summer, autumn, or winter, instead of just the two seasons of rainy and dry. Musim hujan (rainy season) starts in November and ends in March. Musim panas (dry season) starts in April and ends in October. But due to the global climate change the exact seasons are less predictable.
When it rains, it doesn't rain for days, but you could experience heavy rain and light flooding. These rains often take place in the afternoon. After the rain it is often muggy and hot due to the high humidity and lack of wind.
In the dry season it can be dry for months in a row, but some rain might fall in May, June and October. The wind picks up in the dry season and it can be dusty. July is the coolest month.
The temperatures are comfortable in the west of Lombok. They normally don't go over 32 degrees Celcius and there is a light breeze on the island. At night the temperatures will drop to 20-25 degrees Celcius depending on the season.