This the first really warm day and thunder-shower.

May 16. 

E. Hoar saw the henbit (Lamium amplexi caule) a week ago from Mr. Pritchard’s garden. 

Celandine is out a day or more, and rhodora, trillium, and yellow violets yesterday at least. 

Horse-chestnut to-day. 

What handsome long yellow, threadlike peduncles to the staminate flowers of the sugar maple! three inches long, tassel-like, appearing with the leaves. 

A man is about town with a wagon-load of the Rhododendron maximum this evening from Gardiner, Maine. It is well budded; buds nearly an inch long; long, narrow, thick leaves, six inches long or more. He says it means the “rose of Dendrum" and will grow from a mere slip cut off and stuck in any soil, — only water it three times a day!!! No doubt of it. 

It has been oppressively warm to-day, the first really warm, sultry-like weather, so that we were prepared for a thunder-storm at evening. 

At 5 P. M., dark, heavy, wet-looking clouds are seen in the northern horizon, perhaps over the Merrimack Valley, and we say it is going down the river and we shall not get a drop. The main body goes by, there is a shower in the north, and the western sky is suffused with yellow where its thin skirts are withdrawing. 

People stand at their doors in the warm evening, listening to the muttering of distant thunder and watching the forked lightning, now descending to the earth, now ascending to the clouds. This the first really warm day and thunder-shower. 

Had thunder-shower while I was in Haverhill in April.

Nature’appears to have passed a crisis. All slimy reptile life is wide awake. The sprayey dream of the toad has a new sound; from the meadow the hylodes are heard more distinctly; and the tree-toad chirrups often from the elms (?). The sultry warmth and moister air has called him into life. 

We smell the fresher and cooler air from where the storm has passed. 

And now that it has grown dark, the skirts of the cloud seem to promise us a shower. It lightens incessantly right in the west; the right wing of the rear guard of the storm is steadily advancing and firing, and every flash shows the outlines of the cloud. 

We look out into the dark, and ever and anon comes a sudden illumination blinding our eyes, like a vast glow-worm, succeeded ere long by the roll of thunder. 

The first pattering of drops is heard; all west windows are hastily shut. The weak-eyed sit with their backs to windows and close the blinds. 

But we are disappointed, after all, and each flash reveals a narrow strip of evening red through the thin drops below the advancing cloud.

H. D. Thoreau, Journal, May 16, 1853

A man is about town with a wagon-load of the Rhododendron maximum. See June 4, 1853 ("I noticed next day one or more in every front yard on each side of the street, and the inhabitants out watering them. Said to be the most splendid native flower in Massachusetts . . . I hear to-day that one in town has blossomed.")

Yellow violets yesterday at least.  See May 11, 1860 ("Yellow violet, almost; say to-morrow."); May 18, 1856 ("E. Emerson finds half a dozen yellow violets."); May 25, 1852 ("The large yellow woods violet (V. pubescens) by this brook now out"); 

It is going down the river and we shall not get a drop. See June 15, 1860 (“A thunder-shower in the north goes down the Merrimack.”)

This the first really warm day and thunder-shower.   See  April 13, 1858 ("See through the dark rain the first flash of lightning, in the west horizon, doubting if it was not a flash of my eye at first, but after a very long interval I hear the low rumbling of the first thunder, and now the summer is baptized and inaugurated in due form."); May 9, 1859 ("The first thunder this afternoon."); May 10, 1857 ("Before night a sudden shower with some thunder and lightning; the first.”); May 11, 1854 (“ I feel the air cooled and hear the muttering of distant thunder in the northwest and see a dark cloud in that direction indistinctly through the wood. That distant thunder-shower very much cools our atmosphere. I make haste through the woods homeward ...It is surprising what an electrifying effect this shower appears to have had. It is like the christening of the summer.”); May 12, 1858 (“I see now, as I go forth on the river, the first summer shower coming up in the northwest, a dark and well defined cloud with rain falling sheaf-like from it, . . .The thunder-cloud is like the ovary of a perfect flower. . . .. It is not commonly till thus late in the season that the fertile are seen. In the thunder-cloud, so distinct and condensed, there is a positive energy, and I notice the first as the bursting of the pollen-cells in the flower of the sky.”); May 20, 1856 ("Was awaked and put into sounder sleep than ever early this morning by the distant crashing of thunder, and now ... I hear it in mid-afternoon, muttering, crashing in the muggy air in mid-heaven,... like the tumbling down of piles of boards, and get a few sprinkles in the sun. Nature has found her hoarse summer voice again.."); May 29, 1857 ("a first regular summer thunder-shower, preceded by a rush of wind,")