Micro-Season: “Heavy Rain Showers”

We have entered the micro-season of “Heavy Rain Showers”.  This is the third micro-season of the mini-season of Major Heat.  The micro-seasons within Major Heat are:

  • The First Paulownia Fruit Ripen (Jul. 22 –  Jul. 27)
  • Damp Earth Humid Heat (Jul 28 – Aug 01)
  • Heavy Rain Showers  (Aug 02 – Aug 06)

These seasons were established in 1685 by Japanese astronomer Shibuka Shunkai and are specific to Japan. However, just because the calendar focuses on Japan doesn’t mean it isn’t applicable to others.  No matter where you live you can use these seasons as a starting point for your personal exploration of the world around you. 

As a way to celebrate this season, we will explore the water cycle and read some rain-themed haiku by Basho, Issa, and Buson.

The Water Cycle

Rain is just one part of the larger water cycle or hydrological cycle. The water cycle is the process that allows water to move from oceans, to clouds, to streams, and back again.  At its most basic form, the cycle works like this:

  • Ocean water is warmed by the sun, it evaporates, it turns into water vapor, and then rises into the sky
  • As the water vapor rises it begins to cool and condenses into clouds
  • The clouds collect more water vapor until they can’t hold anymore
  • The clouds then begin to release the water in the form of precipitation
  • Depending on the temperature, the precipitation can be in the form of snow, sleet, hail, or rain
  • Once the precipitation hits the ground it either joins the rivers and streams, soaks into the earth, or runs off the surface to join some other body of water such as the ocean.
  • At this point, the water cycle repeats

The above explanation is a very simplified version of this process.  The graphic below created by Dennis Cain at the National Weather Service illustrates many of the ways water moves including transpiration (plants to atmosphere), sublimation (snow and ice directly to gas), and percolation (water into the ground).

Water Cycle Illustration by Dennis Cain/NWS
Water Cycle Illustration by Dennis Cain/NWS


Precipitation is described as an atmospheric phenomenon in which water falls from the sky and reaches the ground.  Precipitation can be either liquid or solid depending on the atmospheric temperature. 

When the atmospheric temperature is below freezing, the precipitation is solid and could be in one of the following forms. These descriptions are courtesy of the National Weather Service.

Ice Pellets or Sleet

Ice pellets or sleet are described as transparent or translucent pellets of ice, which are round or irregular hard grains of ice consisting of frozen raindrops or melted then refrozen snowflakes.


Hail falls in the form of small balls or other pieces of ice falling separately or frozen together in irregular lumps. Associated with thunderstorms, individual hail stones are ¼ inch (5 mm) or greater in diameter. Hail sizes of 1 inch (2.5 cm) or more are indicative of severe thunderstorms.

Snow Pellets

Snow pellets are white, opaque grains of ice that are round or sometimes conical. Diameters are less than ¼ inch (5 mm).


The term “snow” is used to describe snow crystals that are mostly branched and in the form of six-pointed stars.

Ice Crystals

Ice crystals occur in very cold regions. Ice crystals are falling ice that is in the form of needles, columns, or plates. Also called ‘diamond dust’, ice crystals appear like fog with individual water particles forming directly as ice. The shape of the individual ice crystals causes the ‘light pillar’ optical effect above the light source.

When temperatures are above freezing the precipitation is in liquid form and can be in the following forms. These defintions are courtesy of the National Weather Service.


Drizzle is defined as fairly uniform precipitation that is composed exclusively of fine drops very close together. Drizzle appears to float while following air currents, but unlike fog droplets, it falls to the ground. Quite often fog and drizzle occur together.


Rain is the most commonly observed form of precipitation.  When drops are larger than drizzle (0.02 inch / 0.5 mm or more) it is considered rain. However, smaller drops are also considered raindrops if, in contrast to drizzle, they are widely separated.

Photo by Ron Lach on Pexels.com
Photo by Ron Lach

Types Of Rainfall

As this micro-season talks about rainfall, it is important to identify what exactly is “Heavy Rain”. 

“Heavy Rain” is a term associated with a specific rate of rain falling per hour.  There is also light, moderate, and violent rainfall.  The following list explains the difference between these terms.(3) 

  • Light rain falls at a rate of between  a trace to 2.5 millimeters ((0.098 in) per hour
  • Moderate rain falls at a rate of between 2.6 millimeters (0.10 in) to 7.6 millimeters (.30 in) per hour.
  • Heavy rainfall at a rate greater than 7.6 millimeters  (0.30 in) per hour
  • Violent rain falls at a rate greater than 50 millimeters (2.0 in) per hour

Haiku about Rain

Similar to our exploration into dog haiku from last week, the word “rain” is not a seasonal word. Dr. Gabi Greve explains, “Expressions like ‘long rain, strong rain, gentle rain, soft rain, steady rain’ without the mentioning of a specific season are also NOT considered kigo but topics.”(5) The reason for this is that rain can happen during most seasons. As result, to place a rain haiku within a season there needs to be another seasonal word.

Below are a few examples of rain-themed haiku from Basho, Issa, and Buson with various seasonal references.


The rainfall in June –
the poems I’ve pasted to walls
peel off, but leave traces.
a lonely moon:
from the eaves of the temple,
drops of rain

The “a lonely moon” haiku comes from Basho’s Kashima Journal. The World Kigo Database states, “The word moon without further connotation, refers to the autumn moon in Japanese haiku.”(6) This haiku was written alongside many other autumn-themed haiku.


the cut grass
sticks to my feet… 
autumn rain 
three raindrops
a greeting card from heaven...
midsummer heat

These haiku by Issa have very obvious seasonal references with phrases like “autumn rain” and “midsummer heat”.


In the summer rain
the path
has disappeared
the rainy season
and the river with no name
a frightening thing

The “rainy season” is associated with mid-summer. However, some haiku poets consider the rainy season its own season.(7)


  1. “Water Cycle”; National Oceanic and Atmospheric Administration
  2. “Types of Precipitation” National Weather Service
  3. Rain”; Wikipedia
  4. “Types of Precipitation”; National Geographic Resource Library
  5. “Rain”; World Kigo Database
  6. “Moon and related links”; World Kigo Database
  7. “Rainy Season”; World Kido Database

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31 thoughts on “Micro-Season: “Heavy Rain Showers”

Add yours

      1. Where I am in the northeastern part of the US we just have the heat. No substantial rain in days.
        High heat and rain sounds like the perfect mixture for some intense storms!

  1. As I was reading this I was thinking how interesting it would be for a modern Japanese Climatologists familiar with Shibuka Shunkai Microseasons to use it as a reference point for how Japan’s climate has changed since then. I find the very last haiku the most striking since I tend to follow an ideology very similar to the ancient “Way of the Kami” which is older than Shintoism itself. A “river with no name” is basically a flash flood leading to chaos and destruction. To have no name, is to have no place (in the world) and cannot be appeased by respecting its boundaries. There is a psychological distress as old as being human when thoughts, emotions or physical forces assail us and we don’t know how to define it in a way that makes sense with our reality.

    1. Hi Melanie, Thank you for this comment! I feel like your thoughts highlight the idea that a good haiku holds so much more in those short lines than what is often noticed on first glance and that the reader is just as important in the haiku as is the poet. The reader completes the poem.
      Thank you very much for sharing your understanding of the haiku and adding to the conversation!

  2. The pleasure is all mine, Mark! You know I’m quite fond of Japan. The haiku made me think of Hayao Miyazaki’s “Spirited Away.” It’s one of my favorite movies of his. Animations aren’t just for kids, in Japan. This one is for all ages. Maybe you will be willing to give it a try? There is an environmental message in this movie, but it is not heavy handed. Spoiler alert: She saves the river spirit because she remembers its name. (That is how it is related to the haiku.)

    1. I’ll see if I can find “Spirited Away”. I can get into animation. I have a fondness for graphic novels (Although I haven’t read one in a really long time!) so this shouldn’t be that big of a stretch. Thanks for the recommendation!

  3. Great as always – we certainly could do with some rain, love the haiku’s thought you might like one from Jack Kerouac who experimented with the haiku, he thought that, because the English language structure is different from Japanese, western haiku should “simply say a lot in three short lines” – which he does here:

    The Taste of Rain
    Jack Kerouac

    The taste
    Of rain
    – Why kneel?

    I might have a go at doing one myself…I feel a haiku coming on!

    1. I so appreciate Kerouac’s haiku! I have a copy of his book of haiku and enjoy reading it from time to time. Several months ago, Poetry Pea did a Write that Kerouac theme and I submitted several haiku for that theme. A couple were selected for publication! It was very exciting. Thanks for the reminder of Kerouac’s writing! I am looking forward to reading your haiku!

  4. Just want to point out that “a lonely moon: / from the eaves of the temple, / drops of rain” is not from Bashō, but from Sōha. Barnhill points that out in the book you reference, so you much have overlooked the attribution. Not much is known of Sōha except he was a Zen monk who lived near Edo and made that journey with Bashō.

    1. Ah! Very good, thank you! I will go back and make those changes. That you very much for catching that error. Your attention to detail is very much appreciated!

  5. Hello! We are hoping for some rain today in the Seattle, WA area–I can hardly wait for a cool off! I’m guessing this post serves as a prompt, to write rain haiku, yes? If so (and I’d love to), do you want us to follow the form strictly–as in using not just “heavy rain”, but the “season” word? Or can we just write about rain…and hope it fits the haiku–senryu basic 5/7/5 format? Thanks in advance!

    1. Hi Leyde, Very nice to hear from you. I hope you received some rain and got a break from the heat! It is wonderful if you feel inspired to write a rain-inspired haiku and interestingly, I have never thought of these microseasons as writing prompts for the larger community. But, I think you are on to something because it has sort of happened organically. I may have to put some thought into that. Thanks for the great idea! How about for now, if you are up for the challenge, write any senryu or haiku as long as it has the word “rain” in it. The format can either be the 5/7/5 or follow the short/long/short format that isn’t necessarily connect to counting syllables.

      1. Thanks muchly, Mark! We didn’t get the hoped for rain yet…but that won’t stop me from writing a “rain” poem! I really appreciate your thoughtful response–and thanks for the Follow! Take good care, and I’ll see ’round😊

  6. Hey Mark! My rain haiku/senryu will post at midnight 8/11 (Pacific Daylight Time)–hope you enjoy it, I included your link😊

      1. Hi Leyde, The next micro-season post is up and I added an invitation to write your own haiku/senryu based on the season. I linked back to your page as the inspiration for this idea!

      2. Oh my, aren’t you thoughtful and generous–thank you, Mark. However, I’m terrified I won’t be able to measure up regarding the season part–truly, I was only wondering if that was the intention of your prompt…not trying to inspire you at all, hah! But I’ll have a look at your post later and see if the magic will happen😊

  7. Pingback: Rain’s Kiss | Hourglass Poetry

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