Weather and climate are not quite the same. So what is weather, and what is climate?
The main difference between weather and climate is the timescale that they each refer to. Weather describes the conditions of the atmosphere over short periods of time, whilst climate is the average of these conditions over longer time periods.
We generally describe the weather in terms of hourly or daily measurements of temperature, rainfall, cloudiness, sunshine, wind speeds, and so on. Climate usually refers to a region's long-term weather patterns, and can be measured as an average over timescales ranging from months or seasons, to years and longer.
In the words of Robert Heinlein, "Climate is what you expect, weather is what you get". Perhaps even more simply, "Weather is how you choose your outfit, climate is how you choose your wardrobe".
There is natural variability in both weather and climate, but 'climate change' refers to systematic changes across the climate system in response to a forcing agent, which can be natural (e.g. a volcanic eruption) or a result of human activities (e.g. emissions of greenhouse gases from industry or changes in land use). You can read more about our changing climate by following the link to 'What is climate change?'
Global climate is influenced by many interacting systems, including the atmosphere, oceans, land and ice, which together we call the climate system. Changes in the global climate system also affect regional climate, and you can read more about these interactions by following the links below.