Grand Canyon records about 403mm of rain across roughly 38 wet days a year, which is a 10% chance on an average day. August is the wettest month at 52mm (13% of the annual total) and June the driest at 5mm. Local rain type: thunderstorms. The Grand Canyon has dramatic weather variation by elevation — the North Rim receives double the rain (and snow) of the South Rim.
Chance of rain on an average day: 10%
Rainfall climatology for Grand Canyon. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 403mm |
| Rain days per year | 38 |
| Odds on an average day | 10% |
| Wettest month | August — 52mm over 6 days |
| Driest month | June — 5mm over 1 days |
| Rain type | thunderstorms |
| Best dry window | September through November offers dry, comfortable hiking conditions. |
| Worst rain window | July and August bring monsoon thunderstorms — dangerous in narrow side canyons. |
August delivers 940% more rain than June (52mm vs 5mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 13% of the annual total, so rain in Grand Canyon is spread through the year — there is no season you can rely on being dry.
Grand Canyon rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 6 days in August against 1 in June — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 36mm | 4 | 13% | 7°C |
| February | 36mm | 4 | 13% | 7°C |
| March | 36mm | 4 | 13% | 11°C |
| April | 21mm | 2 | 7% | 18°C |
| May | 11mm | 1 | 3% | 25°C |
| June | 5mm | 1 | 3% | 32°C |
| July | 37mm | 4 | 13% | 36°C |
| August | 52mm | 6 | 20% | 36°C |
| September | 36mm | 4 | 13% | 32°C |
| October | 24mm | 3 | 10% | 25°C |
| November | 20mm | 2 | 7% | 18°C |
| December | 38mm | 4 | 13% | 11°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Grand Canyon we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
Grand Canyon records rain on roughly 38 days a year — about a 10% chance on any given day — totalling around 403mm.
August, with about 52mm over 6 rain days. That is 13% of the entire year's rainfall in a single month.
June is the driest month at 5mm across roughly 1 days. September through November offers dry, comfortable hiking conditions.
The Grand Canyon has dramatic weather variation by elevation — the North Rim receives double the rain (and snow) of the South Rim.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.