July
Other strong months: August and June
72/100 weather score
United States · 1991–2020
Best time to visit
Keystone
For Keystone, July has the most comfortable weather in our climate comparison. Typical daytime highs are 23.9°C, nights average 3.9°C, and rainfall totals about 48 mm. Figures use measured 1991–2020 normals from the nearest eligible NOAA station.
Best all-round monthJuly
Typical daytime high23.9°C
Typical night-time low3.9°C
July rainfall48 mm
June
Other strong months: September and August
79/100 weather score
Make the answer personal
Choose the weather
that suits you.
Set the daytime temperature and rainfall you are comfortable with. We will show only the months that meet every choice, using the measured 1991–2020 averages below.
4 months fit your choices for Keystone
The lowest comfort score is 5 out of 100. January, February, March, April, November and December share that score. In January, that is mainly because days reach only -0.5°C, 24° below the 24°C the score treats as ideal, and nights drop to -16.4°C.
Quick answers
Planning a trip to Keystone?
These answers come from the same measured monthly climate record shown on this page.
When is the best time to visit Keystone?
July is the strongest all-round choice in our temperature-and-rainfall comparison, with a typical daytime high of 23.9°C and 48 mm of rain.
What is the hottest month in Keystone?
July is hottest in this record, with a typical daytime high of 23.9°C and a night-time low of 3.9°C.
Which month has the least rain?
November and December have the lowest monthly rainfall total at 22 mm.
Is this a weather forecast?
No. These are long-term measured averages from 1991–2020. Check a current forecast before you travel.
Month by month
See how the weather
changes through the year.
The bars combine daytime temperature, night-time temperature and rainfall. The figures are measured historical averages, not a forecast for a particular trip.
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | -0.5°C | -16.4°C | 24 mm | 7.1 | 9 h 39 | 5 | Strong coverage |
| February | 0.8°C | -15.2°C | 25 mm | 7.3 | 10 h 38 | 5 | Strong coverage |
| March | 4.8°C | -11.3°C | 29 mm | 7.7 | 11 h 49 | 5 | Strong coverage |
| April | 8.7°C | -7.3°C | 36 mm | 8.2 | 13 h 11 | 5 | Strong coverage |
| May | 14.2°C | -2.9°C | 34 mm | 6.9 | 14 h 20 | 32 | Strong coverage |
| June | 20.6°C | 0.8°C | 29 mm | 5.9 | 14 h 57 | 61 | Strong coverage |
| July | 23.9°C | 3.9°C | 48 mm | 9.1 | 14 h 42 | 72 | Strong coverage |
| August | 22.5°C | 3.2°C | 48 mm | 9.6 | 13 h 43 | 66 | Strong coverage |
| September | 19°C | -0.8°C | 36 mm | 7.4 | 12 h 24 | 51 | Strong coverage |
| October | 12.3°C | -5.7°C | 24 mm | 5.7 | 11 h 05 | 22 | Strong coverage |
| November | 5°C | -10.9°C | 22 mm | 6.2 | 9 h 56 | 5 | Strong coverage |
| December | -0.2°C | -15.6°C | 22 mm | 6.5 | 9 h 23 | 5 | Strong coverage |
What has changed
Recent daytime highs are
0.6°C warmer in Keystone.
Each bar shows the difference between the 2011–2025 average daytime high and the 1961–1990 average for the same month at the same station. A blank month does not have enough older observations for a reliable comparison.
Jan
-0.6
Feb
-0.8
Mar
+1.2
Apr
+0.4
May
-0.3
Jun
+1.6
Jul
+0.8
Aug
+0.9
Sep
+1.9
Oct
+0.2
Nov
+1.1
Dec
+0.3
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 16.1°C12 Jan 1953 | -42.2°C19 Jan 1940 | 21 mm18 Jan 1912 | 79 mm1996 · driest 2 mm in 1931 | 115 |
| February | 15.6°C13 Feb 1954 | -42.8°C1 Feb 1951 | 27 mm3 Feb 1936 | 140 mm1936 · driest 3 mm in 1911 | 114 |
| March | 21.7°C22 Mar 2026 | -38.9°C12 Mar 1932 | 47 mm15 Mar 1938 | 98 mm1943 · driest 3 mm in 1913 | 116 |
| April | 24.4°C19 Apr 1946 | -31.7°C1 Apr 1924 | 51 mm21 Apr 1926 | 153 mm1926 · driest 9 mm in 1925 | 115 |
| May | 26.7°C31 May 2002 | -22.2°C6 May 1917 | 48 mm14 May 1928 | 105 mm1917 · driest 5 mm in 1974 | 116 |
| June | 30.6°C21 Jun 1944 | -11.7°C13 Jun 1947 | 37 mm12 Jun 1947 | 79 mm1947 · driest 0 mm in 1980 | 117 |
| July | 31.7°C12 Jul 1939 | -5.6°C7 Jul 1938 | 45 mm19 Jul 2011 | 143 mm1912 · driest 8 mm in 1979 | 116 |
| August | 30.6°C11 Aug 1938 | -6.7°C23 Aug 1928 | 34 mm1 Aug 2023 | 113 mm1936 · driest 3 mm in 1932 | 115 |
| September | 28.9°C4 Sep 1960 | -15.6°C21 Sep 1924 | 51 mm7 Sep 1930 | 147 mm1930 · driest 0 mm in 1944 | 115 |
| October | 25.0°C1 Oct 1944 | -27.2°C28 Oct 1919 | 42 mm15 Oct 1916 | 127 mm1924 · driest 1 mm in 1952 | 114 |
| November | 18.3°C1 Nov 1953 | -34.4°C28 Nov 1915 | 24 mm18 Nov 1930 | 72 mm1950 · driest 1 mm in 1923 | 115 |
| December | 16.1°C11 Dec 1939 | -43.3°C24 Dec 1924 | 31 mm3 Dec 1950 | 123 mm1951 · driest 2 mm in 1911 | 115 |
| Month | Days 25°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|
| January | 0 | 31 | <1 | 10 |
| February | 0 | 28 | <1 | 9 |
| March | 0 | 31 | <1 | 9 |
| April | 0 | 30 | <1 | 9 |
| May | <1 | 27 | <1 | 3 |
| June | 4 | 13 | <1 | <1 |
| July | 13 | 1 | 1 | 0 |
| August | 7 | 3 | 1 | 0 |
| September | 2 | 19 | <1 | <1 |
| October | 0 | 29 | <1 | 4 |
| November | 0 | 30 | <1 | 8 |
| December | 0 | 31 | <1 | 9 |
| Month | Dry days reaching 20°C | Wet days | Days with heavy rain | Weeks with 3+ wet days | Typical high by year |
|---|---|---|---|---|---|
| January | 0% | 23% | 1% | 24% | -3.0–1.9°C |
| February | 0% | 24% | 2% | 25% | -1.6–3.5°C |
| March | <1% | 27% | 2% | 29% | 1.3–6.6°C |
| April | <1% | 26% | 3% | 28% | 6.3–11.3°C |
| May | 14% | 22% | 3% | 22% | 12.3–16.9°C |
| June | 58% | 19% | 2% | 20% | 18.3–22.8°C |
| July | 69% | 29% | 4% | 37% | 22.0–25.2°C |
| August | 65% | 30% | 4% | 35% | 20.9–24.0°C |
| September | 45% | 21% | 3% | 22% | 17.2–21.4°C |
| October | 8% | 17% | 2% | 13% | 10.2–15.6°C |
| November | 0% | 20% | 1% | 19% | 2.3–8.0°C |
| December | 0% | 21% | 1% | 21% | -2.6–3.1°C |
A dry day reaching 20°C records under 1 mm of rain. A wet day records at least 1 mm, while a heavy-rain day records at least 10 mm. The weekly figure is the share of seven-day periods containing three or more wet days. The final column shows the middle 80% of average daytime highs recorded for that month in individual years; a wider range means conditions have varied more from one year to another.
The evidence behind this page
Where these figures
come from.
- Place identity
- GeoNames 5427299
- NOAA station
- USC00052281 · DILLON 1 E
- Station distance
- 4.8 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 29 usable years
- Daylight
- Calculated from latitude 39.60°, mid-month, sunrise to sunset including refraction. Not a station measurement.
- Important limit
- Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.
Next step
Choose your month.
Then plan the details.
The weather comparison for Keystone is based on climate evidence, not payments from travel companies. Flight, accommodation and activity links will be clearly labelled when they are added; there are no booking offers on this page today.
How travel partnerships will work