Greetings, I have stumbled across this article in a 1949 almanac years ago, that described a similar thing called "tha druid calendar", which was a series of plants that one had to keep in mind to forcast the period of the year and the pattern of weather. Sadly I have lost track of this article and I am unaware of the author.

Altho since then I have been looking for similar lore and stories and came across a few...

In Canada (where i come from) the crocus (blue flower) comes up during the last period of snow... as it melts... generally it rains during the days following after. A very small rain tho. After which, the narcissus blooms (yellow flower) and a good 4 to 5 weeks of sun can be expected. During this time, the lilacs starts to bloom (blue flower), and you know that in 2-3 weeks a massive rain is expected (2-3 weeks long), also, the temperature will get over 65F after this point. Following this rain the cherries and apple trees wil flower and there is generally no rain during this period.

I don't know much after this point as these are the reference point to which I usually plant my garden. Usually if I do this before the lilacs finish flowering, I don't have to water my garden ever. As the plants are in tune with the cycles and already seem to know what to expect.

Much later on... when the elder and the ash comes to fruits I know the indian summer is around the corner and that I need to get ready for winter (but this has been changing in the past 2 decades... probably global warming ).

I now reside in Australia, which is a bit different. Here a lot of ppl rely on a tree called murraya or mock orange, which seems to flower a lot more 4-5 days before it rains. Someone else also commented on the morning glory (impopoea or convulus), the same pattern also applies to a lot of other flowers, particularly , the oxalis leafs... shaped like a heart but bent in the middle. They are very accurate plants... when you see them folded upward, it is going to rain in the next few hours, when they are flat, the day is going to be mild with some clouds,, when they are bent downwards it is going to be very sunny.

I also look at the ants a lot as they never go out before a storm.

It's good to pay attention to nature... so many insights. I also love asking old farmers as they all seem to know a thing or two about it. Please keep posting if you find more. Cheers!