Rainy day between sunny ones

[Zante]

Would a rainy day, enough to properly wet the soil, give plants a bit of a boost for nectar production during a period of warm dry weather?

 

[Plenty of honey]

Would a rainy day, enough to properly wet the soil, give plants a bit of a boost for nectar production during a period of warm dry weather?

Yes because the high humidity from the rain(over the leaves) reduces the stress and makes the plant exude more nectar from the flowers, rather than losing water through the leaves in an effort to keep cool.
High humidity slows down "evapotranspiration" so even if the roots are dry because the rain hasn't soaked in to the soil yet, it still has an initial effect on increasing nectar flow.
This helps explain why you get better flows in really hot, close and humid weather.