I usually say, "it's raining today" when it is raining outside. When should I use the expression, "We'll have a rainy day today" instead of "It's going to rain today"?
Could anybody tell me the difference?
I usually say, "it's raining today" when it is raining outside. When should I use the expression, "We'll have a rainy day today" instead of "It's going to rain today"?
Could anybody tell me the difference?
You would use it's going to rain today to say that at some point in the current 24-hour period, rain is expected. Saying it's going to be a rainy day today emphasizes that rain will be the dominant weather pattern of the entire day, whether continuous or at intervals.
But the more customary way to refer to such weather, at least in AmE, is it's going to be rainy today (or it'll be rainy today). When a rainy day is mentioned, either the day or the rain is likely to be metaphorical.
For instance, day can refer to the calendar interval, to any 24-hour period, to daylight hours, or simply your personal agenda:
1a. the period of time when you are awake and doing things
(from Macmillan)
Suppose rain is forecast from 02:00 to 08:00 tomorrow. A dairy farm worker on shift from 03:00 to 11:00 might say it's going to be a rainy day because the rain coincides with most her working day. Her cousin who works at the bank from 09:30 to 18:00 would not, because he will not experience rain in any part of his day, broadly writ.
A rainy day may be understood idiomatically as an unexpected period of difficulty; the notion of saving for a rainy day may go back to the 16th century. To me, the formulation We'll have a rainy day today would particularly invoke the metaphorical sense, predicting a shared experience of an event and not merely the need to carry an umbrella.
A rainy day may refer to a set protocol, for either a literal or metaphorical rainy day, like calling for the use a rainy day fund. My elementary school— in Southern California, quickly paralyzed by a few sprinkles— included extensive parent handbook notations on Rainy Day Dropoff, Rainy Day Assembly, Rainy Day Lunch, and other special procedures; the principal declaring the school day to be a Rainy Day was thus a source of some excitement for us children. But such uses are applicable in only similarly narrow contexts.
A rain day, incidentally, is different. It is either an alternative date for an event that might be postponed or disrupted on account of rain, or a day where work or school is canceled on account of rain (akin to a snow day).