May
May · October · June
89climate match
United States · 1991–2020
Best time to visit
Rocktram.
May leads for comfortable weather in Rocktram: typically 24.6°C by day, 9.9°C at night, with 27 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortMay
Typical high24.6°C
Typical low9.9°C
Rain in May27 mm
July
July · August · September
76climate match
May
May · April · October
86climate match
The weakest month is December, scoring 30 against May’s 89 — days reach only 14.6°C, 9° below the 24°C the score treats as ideal, and nights drop to 4.3°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
3114.7° / 4.6°
Feb
4117.2° / 5.4°
Mar
5519.6° / 6.4°
Apr
7722.2° / 7.5°
May
8924.6° / 9.9°
Jun
8227.8° / 12°
Jul
8228.3° / 13°
Aug
8128.6° / 13°
Sep
7828.9° / 11.9°
Oct
8525.5° / 9.6°
Nov
5918.9° / 6.4°
Dec
3014.6° / 4.3°
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | 14.7°C | 4.6°C | 131 mm | 9.9 | 9 h 46 | 31 | Strong coverage |
| February | 17.2°C | 5.4°C | 135 mm | 9.2 | 10 h 42 | 41 | Strong coverage |
| March | 19.6°C | 6.4°C | 103 mm | 9.3 | 11 h 50 | 55 | Strong coverage |
| April | 22.2°C | 7.5°C | 47 mm | 5.2 | 13 h 08 | 77 | Strong coverage |
| May | 24.6°C | 9.9°C | 27 mm | 3 | 14 h 13 | 89 | Strong coverage |
| June | 27.8°C | 12°C | 6 mm | 0.9 | 14 h 49 | 82 | Strong coverage |
| July | 28.3°C | 13°C | 0 mm | 0 | 14 h 35 | 82 | Strong coverage |
| August | 28.6°C | 13°C | 1 mm | 0.1 | 13 h 39 | 81 | Strong coverage |
| September | 28.9°C | 11.9°C | 2 mm | 0.5 | 12 h 23 | 78 | Strong coverage |
| October | 25.5°C | 9.6°C | 33 mm | 2.9 | 11 h 08 | 85 | Strong coverage |
| November | 18.9°C | 6.4°C | 76 mm | 6.1 | 10 h 03 | 59 | Strong coverage |
| December | 14.6°C | 4.3°C | 137 mm | 9.4 | 9 h 31 | 30 | Strong coverage |
What has changed
Rocktram runs +1.1°C
on the 1961–1990 baseline.
Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.
Jan
+1.6
Feb
+0.9
Mar
+0.7
Apr
+1.7
May
+0.9
Jun
+1.4
Jul
+0.3
Aug
+0.6
Sep
+1.5
Oct
+1.3
Nov
+0.8
Dec
+0.9
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 29.4°C8 Jan 1962 | -7.2°C9 Jan 1937 | 145 mm4 Jan 1982 | 382 mm1909 · driest 1 mm in 2015 | 127 |
| February | 27.2°C28 Feb 1929 | -5.0°C1 Feb 1917 | 109 mm8 Feb 2014 | 388 mm1986 · driest 0 mm in 2022 | 128 |
| March | 33.3°C17 Mar 1914 | -5.0°C8 Mar 1949 | 84 mm14 Mar 2003 | 304 mm1995 · driest 1 mm in 1923 | 128 |
| April | 35.0°C29 Apr 1981 | -2.8°C22 Apr 1929 | 68 mm1 Apr 1996 | 160 mm1896 · driest 0 mm in 1949 | 127 |
| May | 40.0°C30 May 1910 | -1.1°C18 May 1974 | 47 mm16 May 1996 | 95 mm1996 · driest 0 mm in 2017 | 127 |
| June | 45.0°C14 Jun 1961 | 1.1°C17 Jun 1929 | 31 mm2 Jun 1967 | 66 mm2011 · driest 0 mm in 1901 | 127 |
| July | 44.4°C14 Jul 1972 | 3.3°C13 Jul 1929 | 21 mm8 Jul 1974 | 27 mm1974 · driest 0 mm in 1952 | 127 |
| August | 41.7°C15 Aug 2020 | 2.8°C17 Aug 1932 | 21 mm11 Aug 1965 | 33 mm1976 · driest 0 mm in 1931 | 126 |
| September | 45.6°C6 Sep 2022 | 2.2°C22 Sep 1932 | 50 mm23 Sep 1904 | 122 mm1904 · driest 0 mm in 1964 | 126 |
| October | 41.1°C1 Oct 1980 | -2.2°C29 Oct 1946 | 136 mm24 Oct 2021 | 263 mm1962 · driest 0 mm in 2022 | 127 |
| November | 32.2°C16 Nov 1895 | -3.9°C27 Nov 1928 | 149 mm21 Nov 1977 | 267 mm1973 · driest 0 mm in 1936 | 127 |
| December | 27.2°C26 Dec 1967 | -10.0°C22 Dec 1990 | 104 mm27 Dec 1931 | 410 mm1955 · driest 0 mm in 1989 | 126 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) |
|---|---|---|---|---|
| January | <1 | 0 | 5 | 4 |
| February | <1 | 0 | 2 | 5 |
| March | 4 | <1 | <1 | 3 |
| April | 8 | 2 | <1 | 2 |
| May | 13 | 4 | 0 | <1 |
| June | 21 | 9 | 0 | <1 |
| July | 25 | 9 | 0 | 0 |
| August | 26 | 10 | 0 | <1 |
| September | 24 | 12 | 0 | <1 |
| October | 17 | 6 | 0 | <1 |
| November | 2 | <1 | <1 | 3 |
| December | 0 | 0 | 5 | 4 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | 5% | 32% | 15% | 40% | 12.1–16.3°C |
| February | 19% | 31% | 14% | 37% | 13.8–19.1°C |
| March | 36% | 28% | 11% | 31% | 15.8–21.3°C |
| April | 56% | 17% | 5% | 14% | 18.5–23.7°C |
| May | 79% | 8% | 2% | 5% | 21.5–26.4°C |
| June | 95% | 3% | <1% | <1% | 23.8–29.2°C |
| July | 99% | <1% | 0% | 0% | 25.8–29.7°C |
| August | 98% | <1% | <1% | <1% | 25.9–29.5°C |
| September | 96% | 3% | <1% | 2% | 25.2–30.7°C |
| October | 81% | 10% | 4% | 8% | 22.8–27.1°C |
| November | 37% | 21% | 9% | 26% | 16.4–21.1°C |
| December | 5% | 30% | 13% | 35% | 12.1–16.6°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.
The evidence behind this page
Nearby, measured,
and named.
- Place identity
- GeoNames 5388336
- NOAA station
- USC00046074 · NAPA STATE HOSPITAL
- Station distance
- 2.7 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 29 usable years
- Daylight
- Calculated from latitude 38.26°, 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.