Keystone in Summer
In summer (June, July and August), Keystone sees average daytime highs around 89°F and overnight lows near 75°F, with 15.7 in of rain over about 55 wet days across the season. It is the warmest season of the year and the wettest season of the year.
Across summer, daytime highs hold fairly steady around 89°F. The sky is clear or mostly clear about 20% of the time across summer, and the air most often feels oppressive.
Summer is Keystone's weakest season of the year to visit on our travel score. For the whole year in context, see Keystone's year-round climate.
- Avg daytime high
- 89°F
- warmest season of the year
- Avg overnight low
- 75°F
- Rainfall
- 15.7 in
- 55 wet days
- Avg wind
- 5 mph
- Travel score
- 3.3
- weakest season of the year
- Months
- Jun · Jul · Aug
Temperature in Keystone in Summer
Across summer, daytime highs hold fairly steady around 89°F.
A typical summer day in Keystone reaches about 89°F and drops to 75°F overnight. The warmest of the three months is August, the coolest June.
How summer really feels in Keystone
Once humidity and wind are folded in, summer brings about 92 days that feel above 90°F and 0 that feel at or below 32°F.
The story in summer is heat — humidity pushes the afternoon "feels like" well above the raw temperature.
Keystone weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 69° / 51° | 2.5 | 6.5 | 10.4 | 7.1 |
| Feb | 72° / 53° | 2.2 | 6.3 | 11 | 7.4 |
| Mar | 76° / 57° | 2.5 | 6.3 | 11.8 | 7.7 |
| Apr | 82° / 63° | 2.1 | 6 | 12.7 | 7.0 |
| May | 87° / 69° | 2.3 | 7.3 | 13.4 | 5.3 |
| Jun | 89° / 74° | 5.0 | 16.4 | 13.8 | 3.6 |
| Jul | 89° / 76° | 5.0 | 18.3 | 13.6 | 3.2 |
| Aug | 89° / 76° | 5.6 | 19.8 | 13 | 3.1 |
| Sep | 88° / 74° | 4.6 | 14.7 | 12.2 | 3.8 |
| Oct | 84° / 67° | 2.1 | 7.2 | 11.3 | 6.2 |
| Nov | 77° / 58° | 1.4 | 4.3 | 10.6 | 7.9 |
| Dec | 72° / 54° | 2.2 | 6 | 10.2 | 7.5 |
Cloud cover in Summer
The sky is clear or mostly clear about 20% of the time across summer.
Chance of precipitation in Summer
Keystone gets around 15.7 in of rain over 55 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 5 mph across summer.
Sunrise & sunset in Summer
Daylight runs from about 13 h 42 min in early June to 12 h 36 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 5.7 kWh/m².
Hazard calendar for Keystone
In summer, Keystone overlaps its atlantic hurricane and rainy season season. The full year is below, with each hazard's peak months called out.
Keystone sits in the Atlantic hurricane belt; the season peaks August–October.
Keystone's rainy season runs March–March, when most of the year's rain falls.
Is summer a good time to visit Keystone?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a weaker month for outdoor sightseeing in Keystone.
What to pack for Keystone in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Keystone sees daytime highs around 89°F and nights near 75°F. Pack light clothes and rain gear. Worth having: sun protection. About 55 days see rain.
Sea temperature near Keystone in Summer
The nearest coast averages about 85°F across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 16 mi away) is warmest in August at about 86°F and coldest in February near 63°F.
It's comfortable for a long swim from Mar 21 to Dec 11 — about 8.7 months when the water holds above 68°F.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 64 | 63 | 67 | 73 | 78 | 83 | 85 | 86 | 84 | 80 | 73 | 67 |
| Comfort | Cool | Cool | Cool | Refreshing | Warm | Tropical | Tropical | Tropical | Tropical | Warm | Refreshing | Cool |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 64 | Cool |
| Feb | 63 | Cool |
| Mar | 67 | Cool |
| Apr | 73 | Refreshing |
| May | 78 | Warm |
| Jun | 83 | Tropical |
| Jul | 85 | Tropical |
| Aug | 86 | Tropical |
| Sep | 84 | Tropical |
| Oct | 80 | Warm |
| Nov | 73 | Refreshing |
| Dec | 67 | Cool |
UV index in Keystone in Summer
Clear-sky midday UV across summer averages around 11 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Keystone peaks around July 12 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 4 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 5 | 7 | 8 | 9 | 9 | 11 | 11 | 10 | 9 | 7 | 5 | 4 |
| Level | Moderate | High | Very high | Very high | Very high | Extreme | Extreme | Very high | Very high | Very high | High | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 5 | Moderate |
| Feb | 7 | High |
| Mar | 8 | Very high |
| Apr | 9 | Very high |
| May | 9 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Very high |
| Sep | 9 | Very high |
| Oct | 7 | Very high |
| Nov | 5 | High |
| Dec | 4 | Moderate |
Air quality in Keystone in Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer falls, not just the annual average.
Air quality in Keystone is worst in July — around 18 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (November, 9 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 9 | 10 | 10 | 11 | 11 | 16 | 18 | 17 | 12 | 9 | 9 | 9 |
| Level | Good | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 9 | Good |
| Feb | 10 | Good |
| Mar | 10 | Good |
| Apr | 11 | Good |
| May | 11 | Good |
| Jun | 16 | Moderate |
| Jul | 18 | Moderate |
| Aug | 17 | Moderate |
| Sep | 12 | Moderate |
| Oct | 9 | Good |
| Nov | 9 | Good |
| Dec | 9 | Good |
Where is Keystone?
Keystone sits at 28.2°N, 82.6°W, 39 ft above sea level, in United States. The nearest listed city is East Lake, 5.6 mi away.
Topography around Keystone
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Keystone.
Within 2 miles, the terrain around Keystone has only modest variations in elevation — a maximum elevation change of 98 ft around an average of 49 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 138 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 374 ft.
The land around Keystone is covered by trees (46%) and grassland (39%) within 2 miles, trees (56%) and artificial surfaces (20%) within 10 miles, and trees (39%) and water (37%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Keystone (28.1559°, -82.6212°, elevation 39 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.