An area of low pressure is expected to interact with the plume of hot, humid air resident across parts of southern Britain as we head into next week.
The Met Office have already issued an early 'Be aware' warning for the southern half of the UK from Tuesday for the risk of thunderstorms or longer spells of thundery rain - starting in the southwest of the UK before becoming more widespread from Wednesday onwards.
High pressure by Monday and Tuesday will have moved away, allowing a south/southeasterly airflow - this will introduce once again a feed of very warm and this time more humid air up through the UK. Temperatures in the north could peak on Tuesday between 27-30C.
The start of the week will be hot, humid but mainly dry with variable cloud and some sunshine. There is only the outside chance of a sharp, heavy and possibly thundery shower. Overnight temperatures will be uncomfortable for many as the thermometer is not likely to drop much below 18C.
From Tuesday into Wednesday the hot and humid air developing over the UK interacts more widely with a low pressure system containing colder and more unstable air moving in from the southwest by Wednesday. This provides the ingredients for more widespread and energetic storms across the UK - many of us can expect heavy downpours containing hail and thunder.
Large rainfall totals are possible. These are likely to fall in short periods of time and onto hard-baked dry ground - which may lead to localised flooding. As is common in such situations, not everywhere will catch the heaviest of the storms, and a few places may well escape altogether.
The Met Office 'Yellow' Alert covers a broad area at present. As we get closer to the time updates for specific regions will contain more detail in the coming days.
For the latest warnings from the Met Office click here.