United States · 1991–2020

Best time to visit
Rocky.

September leads for comfortable weather in Rocky: typically 24.6°C by day, 10.7°C at night, with 47 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high24.6°C

Typical low10.7°C

Rain in September47 mm

Comfort

September

September · June · August

87climate match

Beach

August

August · July · June

77climate match

Outdoors

May

May · September · October

83climate match

The weakest month is December, scoring 6 against September’s 87 — days reach only 6.8°C, 17° below the 24°C the score treats as ideal, and nights drop to -5.5°C.

Month by month

The whole year,
without the guesswork.

The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.

Jan

107.6° / -4.9°

Feb

77.2° / -5.6°

Mar

2812° / -1.5°

Apr

4015.3° / 1.7°

May

6420.1° / 6.8°

Jun

8127.2° / 12.5°

Jul

7130.7° / 16.1°

Aug

7829° / 14.8°

Sep

8724.6° / 10.7°

Oct

5617.2° / 4°

Nov

3011.8° / -1.1°

Dec

66.8° / -5.5°

Monthly climate evidence for Rocky — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	7.6°C	-4.9°C	18 mm	3.3	9 h 38	10	Good coverage
February	7.2°C	-5.6°C	22 mm	3.8	10 h 38	7	Good coverage
March	12°C	-1.5°C	42 mm	5.1	11 h 49	28	Good coverage
April	15.3°C	1.7°C	66 mm	6.7	13 h 12	40	Good coverage
May	20.1°C	6.8°C	71 mm	7.4	14 h 21	64	Good coverage
June	27.2°C	12.5°C	43 mm	6	14 h 59	81	Good coverage
July	30.7°C	16.1°C	45 mm	6.3	14 h 44	71	Good coverage
August	29°C	14.8°C	49 mm	6.5	13 h 44	78	Good coverage
September	24.6°C	10.7°C	47 mm	5.1	12 h 24	87	Good coverage
October	17.2°C	4°C	34 mm	4.6	11 h 05	56	Good coverage
November	11.8°C	-1.1°C	24 mm	3.9	9 h 55	30	Good coverage
December	6.8°C	-5.5°C	18 mm	3.4	9 h 21	6	Good coverage

Records at RALSTON RSVR, 1978–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	21.7°C21 Jan 2005	-25.6°C16 Jan 2024	22 mm26 Jan 1998	48 mm2019 · driest 1 mm in 2020	29
February	23.3°C11 Feb 2017	-27.2°C3 Feb 2011	47 mm3 Feb 2012	71 mm2012 · driest 1 mm in 2026	29
March	31.1°C22 Mar 2026	-21.1°C4 Mar 2019	45 mm19 Mar 2003	113 mm2003 · driest 0 mm in 2012	29
April	28.9°C13 Apr 2025	-16.7°C10 Apr 2013	51 mm18 Apr 2009	144 mm1999 · driest 1 mm in 2002	30
May	34.4°C30 May 2000	-7.8°C7 May 1978	60 mm12 May 2023	170 mm2015 · driest 12 mm in 2006	30
June	38.9°C26 Jun 2012	0.0°C6 Jun 1998	43 mm5 Jun 2015	122 mm2015 · driest 5 mm in 2012	31
July	38.3°C17 Jul 2003	8.3°C31 Jul 2009	95 mm17 Jul 2000	125 mm2014 · driest 3 mm in 2008	31
August	37.2°C17 Aug 2002	5.6°C2 Aug 1978	54 mm5 Aug 1999	124 mm1999 · driest 6 mm in 2012	29
September	36.7°C3 Sep 2019	-2.2°C29 Sep 1999	267 mm13 Sep 2013	410 mm2013 · driest 1 mm in 2010	30
October	30.6°C3 Oct 2024	-17.2°C30 Oct 2019	37 mm10 Oct 2005	90 mm2009 · driest 2 mm in 2021	29
November	26.1°C3 Nov 2025	-22.8°C14 Nov 2014	25 mm26 Nov 2019	54 mm2015 · driest 0 mm in 2025	28
December	22.2°C23 Dec 2025	-26.1°C22 Dec 2022	40 mm29 Dec 2022	78 mm2006 · driest 0 mm in 2002	29

Typical days per month at RALSTON RSVR, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	25	<1	4
February	0	0	23	<1	4
March	<1	0	19	1	4
April	2	0	11	2	3
May	9	1	3	2	1
June	21	11	0	1	0
July	29	20	0	1	0
August	26	15	0	1	0
September	18	5	<1	1	<1
October	4	0	7	2	2
November	<1	0	18	<1	3
December	0	0	25	<1	4

How often, not how much — every day in RALSTON RSVR’s record sorted by what it was actually like, rather than averaged
Month	Warm & dry days	Wet days	Washouts	Week with 3+ wet days	Daytime mean has ranged
January	<1%	11%	1%	7%	4.1–9.3°C
February	2%	14%	2%	7%	4.6–10.9°C
March	13%	18%	5%	16%	9.7–15.3°C
April	28%	21%	6%	21%	12.5–18.3°C
May	51%	27%	8%	31%	16.9–22.6°C
June	78%	21%	5%	20%	24.1–29.5°C
July	81%	22%	4%	25%	29.2–32.2°C
August	79%	21%	4%	20%	27.4–31.3°C
September	76%	17%	4%	14%	22.7–27.7°C
October	42%	14%	3%	9%	14.8–19.8°C
November	12%	13%	3%	8%	9.1–15.0°C
December	1%	11%	2%	6%	5.0–10.3°C

A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.

1999Each stripe is one year’s mean temperature against the 24-year average. Warmest: 2024. Coolest: 2008.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 5436795
NOAA station: USC00056816 · RALSTON RSVR
Station distance: 3.8 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 22 usable years
Daylight: Calculated from latitude 39.86°, 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.

These places read the same station, so their numbers are identical — distance from RALSTON RSVR is what differs

Golden→Leyden→Leyden Junction→Plastic→Apple Meadows→Eldorado Estates→

Or put two places side by side: Rocky vs Golden

Best time to visitRocky.

September

August

May

The whole year,without the guesswork.

Nearby, measured,and named.

Best time to visit
Rocky.

The whole year,
without the guesswork.

Nearby, measured,
and named.