Template:Portland, Maine weatherbox
| Climate data for Portland International Jetport, Maine (1991–2020 normals,[a] extremes 1871–present[b]) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 67 (19) |
68 (20) |
88 (31) |
92 (33) |
96 (36) |
98 (37) |
103 (39) |
103 (39) |
96 (36) |
88 (31) |
75 (24) |
71 (22) |
103 (39) |
| Mean maximum °F (°C) | 51.8 (11.0) |
51.5 (10.8) |
61.2 (16.2) |
74.5 (23.6) |
85.4 (29.7) |
89.2 (31.8) |
91.6 (33.1) |
90.0 (32.2) |
86.6 (30.3) |
75.3 (24.1) |
65.4 (18.6) |
55.6 (13.1) |
93.5 (34.2) |
| Mean daily maximum °F (°C) | 32.4 (0.2) |
35.0 (1.7) |
42.3 (5.7) |
53.8 (12.1) |
64.2 (17.9) |
73.6 (23.1) |
79.5 (26.4) |
78.7 (25.9) |
71.1 (21.7) |
59.5 (15.3) |
48.4 (9.1) |
38.3 (3.5) |
56.4 (13.6) |
| Daily mean °F (°C) | 24.0 (−4.4) |
26.2 (−3.2) |
34.1 (1.2) |
44.6 (7.0) |
54.9 (12.7) |
64.3 (17.9) |
70.4 (21.3) |
69.2 (20.7) |
61.6 (16.4) |
50.3 (10.2) |
40.0 (4.4) |
30.3 (−0.9) |
47.5 (8.6) |
| Mean daily minimum °F (°C) | 15.6 (−9.1) |
17.3 (−8.2) |
26.0 (−3.3) |
35.4 (1.9) |
45.5 (7.5) |
55.0 (12.8) |
61.2 (16.2) |
59.7 (15.4) |
52.1 (11.2) |
41.0 (5.0) |
31.7 (−0.2) |
22.4 (−5.3) |
38.6 (3.7) |
| Mean minimum °F (°C) | −6.1 (−21.2) |
−2.2 (−19.0) |
6.4 (−14.2) |
23.7 (−4.6) |
33.1 (0.6) |
43.4 (6.3) |
51.7 (10.9) |
48.6 (9.2) |
37.1 (2.8) |
26.5 (−3.1) |
16.0 (−8.9) |
3.9 (−15.6) |
−9.0 (−22.8) |
| Record low °F (°C) | −26 (−32) |
−39 (−39) |
−21 (−29) |
8 (−13) |
23 (−5) |
33 (1) |
40 (4) |
33 (1) |
23 (−5) |
15 (−9) |
−6 (−21) |
−21 (−29) |
−39 (−39) |
| Average precipitation inches (mm) | 3.50 (89) |
3.54 (90) |
4.08 (104) |
4.41 (112) |
3.67 (93) |
4.15 (105) |
3.43 (87) |
3.57 (91) |
3.77 (96) |
5.25 (133) |
4.25 (108) |
4.50 (114) |
48.12 (1,222) |
| Average snowfall inches (cm) | 18.6 (47) |
16.6 (42) |
13.6 (35) |
2.8 (7.1) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.2 (0.51) |
2.3 (5.8) |
14.6 (37) |
68.7 (174) |
| Average precipitation days (≥ 0.01 in) | 11.2 | 10.2 | 11.3 | 11.1 | 12.5 | 11.7 | 10.8 | 9.4 | 9.3 | 10.9 | 10.7 | 12.3 | 131.4 |
| Average snowy days (≥ 0.1 in) | 7.6 | 7.0 | 5.1 | 1.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 1.5 | 6.0 | 28.6 |
| Average relative humidity (%) | 66.8 | 65.2 | 66.3 | 66.8 | 71.1 | 74.7 | 75.3 | 76.3 | 76.7 | 73.9 | 72.6 | 70.2 | 71.3 |
| Average dew point °F (°C) | 11.5 (−11.4) |
12.9 (−10.6) |
21.7 (−5.7) |
30.9 (−0.6) |
42.6 (5.9) |
53.1 (11.7) |
59.2 (15.1) |
58.5 (14.7) |
50.9 (10.5) |
39.7 (4.3) |
30.0 (−1.1) |
17.4 (−8.1) |
35.7 (2.1) |
| Mean monthly sunshine hours | 164.8 | 172.8 | 205.2 | 213.5 | 243.2 | 259.1 | 282.2 | 267.6 | 229.1 | 195.7 | 138.7 | 140.9 | 2,512.8 |
| Percent possible sunshine | 57 | 59 | 55 | 53 | 53 | 56 | 60 | 62 | 61 | 57 | 48 | 51 | 56 |
| Average ultraviolet index | 1 | 2 | 3 | 5 | 7 | 8 | 8 | 7 | 5 | 3 | 2 | 1 | 4 |
| Source 1: NOAA (relative humidity and sun 1961–1990)[2][3][4] | |||||||||||||
| Source 2: Weather Atlas (UV)[5] | |||||||||||||
| Water temperatures | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average sea temperature °F (°C) | 41.3 (5.2) |
38.8 (3.8) |
38.0 (3.3) |
41.6 (5.3) |
46.7 (8.1) |
54.6 (12.6) |
61.3 (16.3) |
63.7 (17.7) |
60.5 (15.8) |
54.9 (12.8) |
49.6 (9.8) |
45.3 (7.4) |
49.7 (9.8) |
| Source: Weather Atlas [5] | |||||||||||||
Notes[edit]
- ^ Mean monthly maxima and minima (i.e. the expected highest and lowest temperature readings at any point during the year or given month) calculated based on data at said location from 1991 to 2020.
- ^ Official records for Portland were kept at downtown from March 1871 to 24 November 1940, and at Portland Int'l Jetport (PWM) since 25 November 1940. Temperature records are limited to the period that PWM was the official site (i.e. since 1940) and are based on the Monthly Weather Summary product issued by the NWS office in Gray, Maine.[1] precipitation and snowfall records date to 1871 and 1882, respectively.
References[edit]
- ^ "Observed Weather Reports". National Oceanic and Atmospheric Administration. Retrieved 2016-09-12.
- ^ "NowData – NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved May 20, 2021.
- ^ "Station: Portland INTL Jetport, ME". U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991–2020). National Oceanic and Atmospheric Administration. Archived from the original on 2023-06-17. Retrieved May 20, 2021.
- ^ "Portland INTL Jetport Climate Normals 1961–1990". National Oceanic and Atmospheric Administration. Archived from the original on 2023-06-17. Retrieved May 20, 2021.
- ^ a b "Portland, Maine, USA - Monthly weather forecast and Climate data". Weather Atlas. Retrieved July 4, 2019.