In haying season, when there is no dew, it indicates rain.
Much dew after a fair day indicates another fair day. A calm and fair day followed by absence of dew indicates rain.
Midnight.
With dew before midnight,
The next day will sure be bright.
Plentiful Dew.
If the dew lies on the grass plentifully after a fair day, it indicates that the following day will be fair. If there is no dew and no wind after a fair day, rain will follow.
Southerly Winds.
A heavy dew in the middle latitudes is said to indicate southerly winds.
A heavy dew with a south to east wind, fair—with a northwest wind, rain. (New England.)