# Climate of Porto

Porto and its metropolitan area feature a Mediterranean climate (Köppen: Csb) with mild wet winters and warm dry summers. According to the Troll-Paffen climate classification, Porto has a warm-temperate subtropical climate (Warmgemäßigt-subtropisches Zonenklima), and a subtropical climate according to Siegmund/Frankenberg. Porto is the wettest major city with a Mediterranean climate.

## Classifications

Porto Climate according to major climate systems :
| Climatic scheme | Initials | Description |
| Köppen system | Csb | warm-summer Mediterranean climate |
| Trewartha system | Cs | Subtropical dry summer |
| Alisov system | — | Subtropical climate |
| Strahler system | — | Marine west coast climate |
| Thornthwaite system | B4 B'2 | Humid Mesothermal |
| Neef system | — | West coast maritime / wet winter climate |

## Temperature
### Normals

Porto has generally moderate temperatures. The average annual high is around 20 °C (68 °F) and average low around 11 °C (52 °F). The climate is also only mildly seasonal, from a maxima of 14 °C (57 °F) in January to 25–26 °C (77–79 °F) in August, while minima is around 5–6 °C (41–43 °F) in January and 15–16 °C (59–61 °F) in July and August. In its metropolitan area, January lows can vary between 7 °C (45 °F) at the coast and 3 °C (37 °F) on the mountainous interior, and August highs vary between 24 °C (75 °F) at the coast and 28 °C (82 °F) in the interior near the Douro valley.
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1981-2010 normals :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean daily maximum °C (°F) | 13.8 (56.8) | 15.0 (59.0) | 17.4 (63.3) | 18.1 (64.6) | 20.1 (68.2) | 23.5 (74.3) | 25.3 (77.5) | 25.7 (78.3) | 24.1 (75.4) | 20.7 (69.3) | 17.1 (62.8) | 14.4 (57.9) | 19.6 (67.3) |
| Daily mean °C (°F) | 9.5 (49.1) | 10.4 (50.7) | 12.6 (54.7) | 13.7 (56.7) | 15.9 (60.6) | 19.0 (66.2) | 20.6 (69.1) | 20.8 (69.4) | 19.5 (67.1) | 16.4 (61.5) | 13.0 (55.4) | 10.7 (51.3) | 15.2 (59.4) |
| Mean daily minimum °C (°F) | 5.2 (41.4) | 5.9 (42.6) | 7.8 (46.0) | 9.1 (48.4) | 11.6 (52.9) | 14.5 (58.1) | 15.9 (60.6) | 15.9 (60.6) | 14.7 (58.5) | 12.2 (54.0) | 8.9 (48.0) | 6.9 (44.4) | 10.7 (51.3) |
| Source: IPMA ||||||||||||||
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1971-2000 normals :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean daily maximum °C (°F) | 13.5 (56.3) | 14.8 (58.6) | 16.8 (62.2) | 17.7 (63.9) | 19.4 (66.9) | 22.8 (73.0) | 25.0 (77.0) | 25.0 (77.0) | 23.7 (74.7) | 20.4 (68.7) | 16.8 (62.2) | 14.4 (57.9) | 19.2 (66.5) |
| Daily mean °C (°F) | 9.3 (48.7) | 10.4 (50.7) | 11.9 (53.4) | 13.2 (55.8) | 15.2 (59.4) | 18.3 (64.9) | 20.2 (68.4) | 20.1 (68.2) | 18.9 (66.0) | 16.0 (60.8) | 12.6 (54.7) | 10.6 (51.1) | 14.7 (58.5) |
| Mean daily minimum °C (°F) | 5.0 (41.0) | 5.9 (42.6) | 7.1 (44.8) | 8.6 (47.5) | 11.0 (51.8) | 13.8 (56.8) | 15.5 (59.9) | 15.2 (59.4) | 14.1 (57.4) | 11.5 (52.7) | 8.3 (46.9) | 6.8 (44.2) | 10.2 (50.4) |
| Source: IPMA ||||||||||||||
Climate data for Porto São Gens, elevation: 90 m or 300 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean daily maximum °C (°F) | 13.6 (56.5) | 14.6 (58.3) | 16.4 (61.5) | 17.3 (63.1) | 19.0 (66.2) | 22.3 (72.1) | 24.4 (75.9) | 24.5 (76.1) | 23.3 (73.9) | 20.2 (68.4) | 16.9 (62.4) | 14.5 (58.1) | 18.9 (66.0) |
| Daily mean °C (°F) | 9.7 (49.5) | 10.7 (51.3) | 12.1 (53.8) | 13.1 (55.6) | 15.0 (59.0) | 17.9 (64.2) | 19.8 (67.6) | 19.7 (67.5) | 18.7 (65.7) | 15.9 (60.6) | 12.8 (55.0) | 10.8 (51.4) | 14.7 (58.4) |
| Mean daily minimum °C (°F) | 5.7 (42.3) | 6.8 (44.2) | 7.8 (46.0) | 8.9 (48.0) | 11.0 (51.8) | 13.5 (56.3) | 15.2 (59.4) | 14.8 (58.6) | 14.1 (57.4) | 11.6 (52.9) | 8.8 (47.8) | 7.1 (44.8) | 10.4 (50.8) |
| Source: IPMA ||||||||||||||
Climate data for Francisco Sá Carneiro Airport, elevation: 70 m or 230 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean daily maximum °C (°F) | 13.8 (56.8) | 14.7 (58.5) | 16.5 (61.7) | 17.3 (63.1) | 19.0 (66.2) | 22.1 (71.8) | 24.1 (75.4) | 24.2 (75.6) | 23.1 (73.6) | 20.1 (68.2) | 16.8 (62.2) | 14.6 (58.3) | 18.9 (66.0) |
| Daily mean °C (°F) | 9.6 (49.3) | 10.5 (50.9) | 11.9 (53.4) | 13.0 (55.4) | 14.9 (58.8) | 17.7 (63.9) | 19.4 (66.9) | 19.3 (66.7) | 18.4 (65.1) | 15.8 (60.4) | 12.7 (54.9) | 10.8 (51.4) | 14.5 (58.1) |
| Mean daily minimum °C (°F) | 5.4 (41.7) | 6.4 (43.5) | 7.3 (45.1) | 8.6 (47.5) | 10.8 (51.4) | 13.3 (55.9) | 14.7 (58.5) | 14.4 (57.9) | 13.6 (56.5) | 11.4 (52.5) | 8.6 (47.5) | 7.0 (44.6) | 10.1 (50.2) |
| Source: IPMA ||||||||||||||

### Extremes

Due to its coastal position, temperatures below freezing (0 °C (32 °F)) are rare, and frosts are never severe. Porto is placed in the USDA hardiness zone 10a. The lowest temperature ever recorded in the city was −4.1 °C (24.6 °F) on 11 January 1941.
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1981-2010 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 23.3 (73.9) | 23.2 (73.8) | 28.5 (83.3) | 30.2 (86.4) | 34.1 (93.4) | 38.7 (101.7) | 40.0 (104.0) | 40.9 (105.6) | 36.9 (98.4) | 32.2 (90.0) | 26.3 (79.3) | 24.8 (76.6) | 40.9 (105.6) |
| Record low °C (°F) | −3.3 (26.1) | −2.8 (27.0) | −1.6 (29.1) | −0.1 (31.8) | 3.3 (37.9) | 5.6 (42.1) | 9.5 (49.1) | 8.0 (46.4) | 5.5 (41.9) | 1.4 (34.5) | −0.3 (31.5) | −1.2 (29.8) | −3.3 (26.1) |
| Source: IPMA ||||||||||||||
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 22.3 (72.1) | 23.2 (73.8) | 28.0 (82.4) | 28.9 (84.0) | 34.1 (93.4) | 38.7 (101.7) | 38.3 (100.9) | 37.6 (99.7) | 36.9 (98.4) | 32.2 (90.0) | 26.3 (79.3) | 24.8 (76.6) | 38.7 (101.7) |
| Record low °C (°F) | −3.3 (26.1) | −2.8 (27.0) | −1.3 (29.7) | 0.1 (32.2) | 3.3 (37.9) | 5.6 (42.1) | 9.5 (49.1) | 8.0 (46.4) | 5.5 (41.9) | 1.4 (34.5) | −0.3 (31.5) | −1.2 (29.8) | −3.3 (26.1) |
| Source: IPMA ||||||||||||||
Climate data for Porto São Gens, elevation: 90 m or 300 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 22.0 (71.6) | 23.6 (74.5) | 27.6 (81.7) | 29.0 (84.2) | 33.6 (92.5) | 39.0 (102.2) | 38.0 (100.4) | 37.6 (99.7) | 36.5 (97.7) | 32.5 (90.5) | 25.0 (77.0) | 25.0 (77.0) | 39.0 (102.2) |
| Record low °C (°F) | −3.0 (26.6) | −2.0 (28.4) | −2.0 (28.4) | 0.0 (32.0) | 0.5 (32.9) | 4.0 (39.2) | 8.0 (46.4) | 7.0 (44.6) | 4.0 (39.2) | 1.0 (33.8) | −2.0 (28.4) | −2.5 (27.5) | −3.0 (26.6) |
| Source: IPMA ||||||||||||||
Climate data for Francisco Sá Carneiro Airport, elevation: 70 m or 230 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 23.3 (73.9) | 24.4 (75.9) | 27.6 (81.7) | 28.2 (82.8) | 33.5 (92.3) | 38.3 (100.9) | 37.7 (99.9) | 37.1 (98.8) | 36.4 (97.5) | 31.7 (89.1) | 26.3 (79.3) | 24.8 (76.6) | 38.3 (100.9) |
| Record low °C (°F) | −3.5 (25.7) | −3.8 (25.2) | −2.6 (27.3) | −0.1 (31.8) | 1.5 (34.7) | 5.4 (41.7) | 8.0 (46.4) | 6.1 (43.0) | 5.0 (41.0) | 1.0 (33.8) | −1.1 (30.0) | −2.5 (27.5) | −3.8 (25.2) |
| Source: IPMA ||||||||||||||

## Precipitation

Porto has abundant levels of precipitation. Despite averaging above 1,000 mm (39 in) of precipitation a year, July and August are relatively dry with around 15–30 mm (0.59–1.18 in) falling each month. The wettest period is between October and February, mostly between October and December, the wettest month.
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1981-2010 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average precipitation mm (inches) | 147.1 (5.79) | 110.5 (4.35) | 95.6 (3.76) | 117.6 (4.63) | 89.6 (3.53) | 39.9 (1.57) | 20.4 (0.80) | 32.9 (1.30) | 71.9 (2.83) | 158.3 (6.23) | 172.0 (6.77) | 181.0 (7.13) | 1,237 (48.7) |
| Source: IPMA ||||||||||||||
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1971-2000 normals :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average precipitation mm (inches) | 157.6 (6.20) | 139.7 (5.50) | 89.9 (3.54) | 115.6 (4.55) | 97.6 (3.84) | 46.0 (1.81) | 18.3 (0.72) | 26.7 (1.05) | 71.0 (2.80) | 138.0 (5.43) | 158.4 (6.24) | 194.7 (7.67) | 1,253.5 (49.35) |
| Source: IPMA ||||||||||||||
Climate data for Porto São Gens, elevation: 90 m or 300 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average precipitation mm (inches) | 153.2 (6.03) | 136.8 (5.39) | 88.0 (3.46) | 109.2 (4.30) | 92.7 (3.65) | 46.2 (1.82) | 18.0 (0.71) | 23.9 (0.94) | 71.6 (2.82) | 138.1 (5.44) | 160.1 (6.30) | 186.5 (7.34) | 1,224.3 (48.2) |
| Source: IPMA ||||||||||||||
Climate data for Francisco Sá Carneiro Airport, elevation: 70 m or 230 ft, 1971-2000 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average precipitation mm (inches) | 142.4 (5.61) | 126.7 (4.99) | 81.5 (3.21) | 96.4 (3.80) | 89.4 (3.52) | 42.9 (1.69) | 16.5 (0.65) | 23.3 (0.92) | 61.6 (2.43) | 132.1 (5.20) | 152.9 (6.02) | 181.4 (7.14) | 1,147.1 (45.18) |
| Source: IPMA ||||||||||||||

## Humidity

The average relative humidity is around 77%. 81% from November to January and 73% in the summer. Summer can be slightly muggy in the hottest days but is generally comfortable, as temperatures rarely surpass 30 °C (86 °F).
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1961-1990 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average relative humidity (%) | 81 | 80 | 75 | 74 | 74 | 74 | 73 | 73 | 76 | 80 | 81 | 81 | 77 |
| Source: NOAA ||||||||||||||

## Other phenomena
### Sunshine, UV and daylight

Despite its precipitation, the total hours of sunshine are relatively normal for a region of its latitude. Winters, especially December, are somewhat dull, and summers are sunny.
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1961-1990 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean monthly sunshine hours | 124.0 | 129.0 | 192.0 | 217.0 | 258.0 | 274.0 | 308.0 | 295.0 | 224.0 | 184.0 | 139.0 | 124.0 | 2,468 |
| Mean daily daylight hours | 9.6 | 10.7 | 12.0 | 13.3 | 14.5 | 15.1 | 14.8 | 13.8 | 12.5 | 11.1 | 9.9 | 9.3 | 12.2 |
| Percent possible sunshine | 40 | 42 | 52 | 55 | 55 | 61 | 66 | 68 | 63 | 54 | 46 | 44 | 54 |
| Average ultraviolet index | 2 | 3 | 4 | 6 | 7 | 8 | 8 | 8 | 6 | 4 | 2 | 1 | 5 |
| Source 1: NOAA ||||||||||||||
| Source 2: Weather Atlas ||||||||||||||
Climate data for Porto (Fontainhas), elevation: 93 m or 305 ft, 1987-2007 :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean monthly sunshine hours | 142.4 | 155.0 | 199.6 | 221.9 | 276.4 | 277.3 | 302.1 | 284.8 | 230.1 | 162.0 | 139.3 | 118.2 | 2,509.1 |
| Source: German Meteorological Service ||||||||||||||

### Wind

As a coastal Atlantic city, winds are most predominant in winter. In the summer, nortada winds prevail and can refresh the city in the hottest days. The city centre is sheltered and seldom gets any strong winds.
Average wind speed (km/h) 1971-2000 :
| | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Porto (Fontainhas) | 19.6 | 19.7 | 19.2 | 19.0 | 18.1 | 16.9 | 17.3 | 16.3 | 15.2 | 16.8 | 18.4 | 20.0 | 18.0 |
| Porto São Gens | 8.6 | 8.7 | 8.8 | 9.0 | 8.3 | 7.7 | 7.4 | 6.8 | 6.5 | 6.5 | 6.5 | 6.9 | 8.4 |
| Porto Pedras Rubras | 15.7 | 16.3 | 15.0 | 15.0 | 14.9 | 13.5 | 12.5 | 12.2 | 11.9 | 13.3 | 14.2 | 16.3 | 14.2 |

## Sea Temperature

Average sea temperature, according to seatemperature.org: :
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| 14.3 °C (57.7 °F) | 13.8 °C (56.8 °F) | 13.8 °C (56.8 °F) | 14.9 °C (58.8 °F) | 16.2 °C (61.2 °F) | 17.2 °C (63.0 °F) | 17.3 °C (63.1 °F) | 17.9 °C (64.2 °F) | 18.3 °C (64.9 °F) | 17.8 °C (64.0 °F) | 16.8 °C (62.2 °F) | 15.4 °C (59.7 °F) | 16.1 °C (61.0 °F) |
Average sea temperature, according to surf-forecast.com: :
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| 14.5 °C (58.1 °F) | 13.5 °C (56.3 °F) | 14.0 °C (57.2 °F) | 14.5 °C (58.1 °F) | 15.5 °C (59.9 °F) | 17.5 °C (63.5 °F) | 18.5 °C (65.3 °F) | 19.0 °C (66.2 °F) | 18.5 °C (65.3 °F) | 17.5 °C (63.5 °F) | 16.0 °C (60.8 °F) | 15.5 °C (59.9 °F) | 16.2 °C (61.2 °F) |

## 1961-1990 data

Climate data for Porto (Fontainhas), elevation: 100 m or 330 ft, 1961-1990 normals and extremes :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °C (°F) | 22.3 (72.1) | 22.7 (72.9) | 26.5 (79.7) | 27.5 (81.5) | 34.7 (94.5) | 38.7 (101.7) | 38.3 (100.9) | 38.2 (100.8) | 36.9 (98.4) | 32.2 (90.0) | 27.7 (81.9) | 24.8 (76.6) | 38.7 (101.7) |
| Mean daily maximum °C (°F) | 13.5 (56.3) | 14.3 (57.7) | 16.2 (61.2) | 17.5 (63.5) | 19.6 (67.3) | 22.7 (72.9) | 24.7 (76.5) | 25.0 (77.0) | 24.0 (75.2) | 20.9 (69.6) | 16.7 (62.1) | 13.9 (57.0) | 19.1 (66.4) |
| Daily mean °C (°F) | 9.3 (48.7) | 10.1 (50.2) | 11.5 (52.7) | 12.9 (55.2) | 15.1 (59.2) | 18.1 (64.6) | 19.9 (67.8) | 19.8 (67.6) | 19.0 (66.2) | 16.2 (61.2) | 12.3 (54.1) | 9.9 (49.8) | 14.5 (58.1) |
| Mean daily minimum °C (°F) | 5.1 (41.2) | 5.9 (42.6) | 6.8 (44.2) | 8.3 (46.9) | 10.6 (51.1) | 13.5 (56.3) | 15.0 (59.0) | 14.6 (58.3) | 13.9 (57.0) | 11.4 (52.5) | 7.9 (46.2) | 5.9 (42.6) | 9.9 (49.8) |
| Record low °C (°F) | −3.3 (26.1) | −3.0 (26.6) | −1.8 (28.8) | 0.1 (32.2) | 2.6 (36.7) | 5.6 (42.1) | 9.0 (48.2) | 8.0 (46.4) | 5.5 (41.9) | 1.4 (34.5) | −0.6 (30.9) | −2.1 (28.2) | −3.3 (26.1) |
| Average precipitation mm (inches) | 171.0 (6.73) | 169.0 (6.65) | 112.0 (4.41) | 112.0 (4.41) | 89.0 (3.50) | 53.0 (2.09) | 16.0 (0.63) | 22.0 (0.87) | 64.0 (2.52) | 131.0 (5.16) | 152.0 (5.98) | 176.0 (6.93) | 1,267 (49.88) |
| Average precipitation days (≥ 1.0 mm) | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 | 6.0 | 2.0 | 3.0 | 6.0 | 10.0 | 12.0 | 12.0 | 108 |
| Average relative humidity (%) | 81.0 | 80.0 | 75.0 | 74.0 | 74.0 | 74.0 | 73.0 | 73.0 | 76.0 | 80.0 | 81.0 | 81.0 | 76.8 |
| Mean monthly sunshine hours | 124.0 | 129.0 | 192.0 | 217.0 | 258.0 | 274.0 | 308.0 | 295.0 | 224.0 | 184.0 | 139.0 | 124.0 | 2,468 |
| Source: NOAA ||||||||||||||