Rain or Shine is an open textbook that consists of 242 pages and 13 chapters that cover fundamental concepts in soil physics and vadose zone hydrology. The textbook is aimed at upper-level undergraduate students and graduate students at the master's level pursuing a degree in soil science, crop science, agronomy, environmental science, or hydrology. The book covers most of the soil physics topics included in the Soil Science Performance Objectives defined by the Soil Science Society of America's Council of Soil Science Examiners. Thus, this book can be helpful for students and practitioners preparing to become certified professional soil scientists. The latest version of the book is available for free through the Open Science Framework repository (https://osf.io/z4rbt/) and the author's institutional website (http://soilphysics.okstate.edu/) in the Portable Document Format (PDF, file size of 10 MB), which allows for easy electronic distribution in websites, email, and learning management systems. The book has clear prose, a logical organization of the content, and well-articulated examples that allow readers to relate soil physical properties and processes to aspects of everyday life. All formal definitions in terms of mathematical equations are presented at the algebraic level. Readers that complete this book will be equipped with the necessary foundation to take more advanced soil physics courses with a greater focus on differential equations. Each chapter clearly states the learning objectives and engages the reader through multiple media components including images, tables, videos, and hyperlinks to additional informative content. Several videos were recorded by the author himself and provide worked examples that complement the book material and provide a more immersive learning experience than traditional books. All images and tables have descriptive captions and appropriately indicate the source and corresponding license of the reference material. Most chapters also include a problem set that consists of study questions and practical problems. A problem set key is available from the author of the book upon request (and thus is not accessible by students). Chapter 1 contains the author's motivation for the book, a practical introduction to the International System of Units, and a list of additional resources to review basic concepts in physics, mathematics, and soil science. Chapter 2 covers the hierarchical spatial organization of soils from global patterns to the primary soil particles. In this chapter, the author introduces key concepts such as soil structure, aggregate stability, soil texture, and particle size distribution. This chapter also introduces the Visual Evaluation of Soil Structure method, which can be easily adapted into a complementary field or laboratory exercise. Practical real-world examples are provided related to climate change, agricultural management, and pesticide transport in the soil. Chapter 3 introduces the concepts of soil water content, soil water potential, and soil water retention curves. This section has particular emphasis on mass–volume relationships like gravimetric water content, volumetric water content, and soil water storage. This chapter also includes detailed description of methods and instruments used to measure soil water content and soil water potential. Chapter 4 covers saturated and unsaturated soil water flow in soils. This chapter covers the concept of hydraulic gradient, hydraulic equilibrium, and soil hydraulic conductivity. Chapters 5–11 cover the dominant soil physical processes by following the fate of a raindrop through Earth's soil water balance. Chapter 5 starts with a description of soil water inputs like precipitation and irrigation. Special attention is given to global precipitation spatial patterns, precipitation amount, and precipitation intensity. This chapter also emphasizes canopy and litter interception, raindrop impact, and crust formation due to physical dispersion. Chapter 6 describes the infiltration process, infiltration models, and infiltration measurements in field conditions. Chapter 7 covers runoff and the stages of soil erosion by water. Chapter 8 presents the process of soil water redistribution and drainage. This chapter includes the definition of practical concepts like field capacity and an interesting discussion on the potential environmental impacts of drainage. Chapter 9 is closely related to the previous chapter and covers solute transport and groundwater pollution in agricultural soils. This chapter introduces the concepts of advection, diffusion, hydrodynamic dispersion, and sorption of solutes. The chapter also includes a comprehensive presentation of preferential flow in soils. Chapter 10 covers the evaporation process, salinization, and soil erosion by wind. This chapter represents the bridge between the soil water balance and the surface energy balance. The chapter includes excellent content on the impact of drought and poor management practices on the Dust Bowl in the U.S. Great Plains. Chapter 11 presents plant transpiration and root water uptake with emphasis on the continuous pathways along the soil–plant–atmosphere continuum. The chapter describes plant transpiration responses to soil moisture conditions characterized by the energy-state of water in the soil. Chapters 12 and 13 cover the nature and fate of solar radiation received at the land surface. Chapter 12 describes in detail the modes of heat transfer in the soil, the components of the surface energy balance, and the impact of land management and soil physical properties on the phenomenon of climate change. Chapter 13 covers heat transfer, surface and subsurface soil temperature, and soil thermal properties (heat capacity, thermal conductivity, and thermal diffusivity). The book could benefit from additional chapters on gas transport, and soil mechanics and engineering properties, which are the only sections of the soil physics portion of the Soil Science Fundamentals Exam Performance Objectives not currently present in the book. Since the book is available under the Creative Commons License, anyone can contribute with additional chapters. However, the textbook is currently only available in PDF format, which limits the ability of others to edit or comment on the book. Perhaps the adoption of a different platform more amenable to collaborative writing like Wikibooks (https://en.wikibooks.org), GitBook (https://www.gitbook.com/), or the implementation of annotation tools (e.g., hypothesis: https://web.hypothes.is/) could benefit the participation of other authors. A distinct advantage of this open textbook is that the author has been consistently updating the book every year to keep information relevant and incorporating feedback from students and teachers alike. This book is insightful, easy to read, and presents a refreshing and integrated view of modern soil physics. We highly recommend this book to students, teachers, and practitioners in the fields of agronomy, soil science, environmental science, and hydrology. The authors of this review have been using the Rain or Shine textbook for the past three years as the reference textbook for a dual-level (i.e., undergraduate and graduate-level) course in Environmental Soil Physics at Kansas State University (Patrignani), Texas A&M University (Wyatt), Auburn University (Knappenberger), Humboldt State University (Marshall), and Oklahoma State University (Wyatt); it has had a great reception from students: “I really enjoy the textbook; it is very easy to understand and explains materials perfectly for someone new to soils. The videos included in the online textbook are usually very helpful on the homework. I also find that having a deeper understanding of the physical context of what the equations we learn to measure.” Spring 2020, Oklahoma State University. The development of this textbook was supported in part by the Wise Oklahoma State University Library Open Textbook Initiative. This review was supported by the Kansas Agricultural Experiment Station (Contribution 22-217-J).