August scores 75/100 for outdoor ceremonies: low rain risk (5 wet days, 30mm), 24°C afternoons cooling to about 14°C for the reception, and 13.8 hours of daylight for the photography schedule. December is the month to avoid at 18/100.
August outdoor ceremony score: 75/100
Climate normals for Sun Valley rescored on wedding-specific weighting. Once your date falls inside the 14-day window the live forecast on this page takes over.
Conditions on this page are recalculated from the latest forecast every time it is opened, for the current date in the location's own time zone. Showing .
| Best wedding month | August — 75/100 |
| Second choice | July — 69/100 |
| Month to avoid | December — 18/100 |
| Rain risk in the best month | Low — rain on about 5 days |
| Guest comfort | 92/100 at 24°C |
| Reception temperature | ≈ 14°C after sunset in August |
| Photo light | 10h of sun across a 13.8h day |
| Months scoring 65+ | 2 of 12 |
August keeps seated guests at 24°C in the afternoon and around 14°C after sunset — the closest Sun Valley gets to a ceremony that needs neither shade structures nor patio heaters.
Rain falls on roughly 5 days in August (low risk, 30mm). A simple marquee-on-standby is usually enough.
August gives 13.8 hours of daylight and about 10 hours of direct sun per day, so a late-afternoon ceremony puts portraits inside golden hour rather than after it.
December scores 18/100 for weddings in Sun Valley: 5°C highs, 66mm of rain and -3°C evenings make a fully outdoor plan fragile.
Scored on rain risk, guest comfort, evening temperature and photographic light — deliberately different weighting from the travel score.
| Month | Wedding score | Rain risk | Afternoon | Evening | Guest comfort | Photo light |
|---|---|---|---|---|---|---|
| January | 28/100 | Moderate (8 days) | 3°C | -5°C | 35/100 | 33/100 |
| February | 27/100 | Moderate (9 days) | 5°C | -3°C | 42/100 | 32/100 |
| March | 24/100 | Moderate (11 days) | 9°C | 1°C | 56/100 | 21/100 |
| April | 30/100 | Moderate (13 days) | 15°C | 6°C | 76/100 | 19/100 |
| May | 41/100 | Moderate (13 days) | 20°C | 10°C | 93/100 | 28/100 |
| June | 51/100 | Moderate (11 days) | 24°C | 14°C | 92/100 | 42/100 |
| July | 69/100 | Low (7 days) | 26°C | 16°C | 83/100 | 77/100 |
| August | 75/100 | Low (5 days) | 24°C | 14°C | 92/100 | 81/100 |
| September | 63/100 | Low (7 days) | 20°C | 10°C | 93/100 | 65/100 |
| October | 35/100 | Moderate (11 days) | 15°C | 6°C | 76/100 | 26/100 |
| November | 23/100 | Moderate (11 days) | 9°C | 1°C | 56/100 | 17/100 |
| December | 18/100 | Moderate (11 days) | 5°C | -3°C | 42/100 | 16/100 |
Wedding weather is scored differently from travel weather: seated guests in formalwear tolerate a narrower band than sightseers, and the ceremony hour matters more than the daily average. Each month in Sun Valley is scored 0–100 on the weighting below.
| Factor | Weight | What it measures |
|---|---|---|
| Dry conditions | 38% | Share of days with measurable rain — the single factor most likely to force a backup plan. |
| Guest comfort | 27% | Distance from a 22°C daytime ideal, with an extra penalty for humid heat above 24°C. |
| Evening temperature | 20% | Modelled reception-hour temperature against an 18°C ideal for an outdoor evening. |
| Photo light | 15% | Sunshine hours and daylight length, which set the length and quality of the golden hour window. |
Based on long-run climate averages rather than a forecast. Plan the ceremony around the golden hour — see golden hour times for Sun Valley linked below.
August, at 75/100. It combines low rain risk with 24°C afternoons and roughly 14°C evenings, which is the most forgiving combination Sun Valley offers for seated guests.
December scores 18/100: 5°C highs, 66mm of rain over about 11 days and -3°C evenings make a fully outdoor plan fragile.
In August rain falls on roughly 5 of 30 days, so the single-day probability is about 17%. In December that rises to about 37%.
A marquee on standby is usually enough in August, where rain risk is low. Outside the 2 months scoring 65 or higher, book real covered space.
August gives 13.8 hours of daylight and about 10 hours of direct sun. Put portraits in the final 60–90 minutes of daylight so they land inside golden hour rather than after it.