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Central Valley Region

Weather > Central Valley Region

Central Valley Region

Written By: Ryan Van Velzer
Last updated: Nov 01, 2022

Costa Rica's Central Valley is the urban population center for good reason, with daily average temperatures between 72 and 75 degrees, the Central Valley has the mildest climate in the whole country. 

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The Central Valley weather region includes parts of the provinces of Heredia, San Jose, Alajuela and Cartago, including popular cities like San Jose, Heredia, Escazu, Santa Ana, Cartago, Barva and Grecia, among many others.

Max average temperatures rarely exceed 84 degrees while the lowest average temperatures are a mere 64 degrees. Relative humidity averages about 75 percent, dropping to 69 percent during the dry season.

The dry season runs from December to March, with April and November being months of transition. During the dry season, the humidity is lower. The months of January through March are also marked with persistent northeast winds and lots of sunshine. 

The wet season months of May through November are characterized by less sun and more rain. July tends to be the driest of the wet months and is considered a miniature dry season.  Usually, you get at least four hours of sun in the morning before the afternoon storms develop. September and October are the rainiest months (averaging 26 inches per month) of the year, and the most humid. The Central Valley weather region receives 77.4 inches of annual rainfall.

As you ascend into the mountains north of Heredia, especially up past Barva, the weather tends to be cooler and cloudier.

Alajuela

MonthAverage HighsAverage LowsAverage RainfallHumidity
 FCFCin.mm%
Jan. 81 27 62 17 0.28 7 69
Feb. 83 28 62 17 0.47 12 69
Mar. 85 29 63 17 0.55 14 67
Apr. 85 29 63 17 3.23 82 70
May 82 28 64 18 10.67 271 82
Jun. 81 27 64 18 10.63 270 82
Jul. 81 27 64 18 7.09 180 84
Aug. 81 27 63 17 10.16 258 79
Sep. 80 27 63 17 13.7 348 82
Oct. 80 27 63 17 13.39 340 87
Nov. 80 27 63 17 19.57 497 86
Dec. 81 27 63 17 20.87 530 80

Cartago

MonthAverage HighsAverage LowsAverage RainfallHumidity
FCFCin.mm%
Jan. 73 23 55 13 1.2 31 78
Feb. 74 23 54 12 0.73 19 79
Mar. 77 25 55 13 0.6 16 77
Apr. 78 26 56 13 1.85 48 79
May 79 26 58 14 7.27 187 83
Jun. 77 25 57 14 7.87 202 83
Jul. 77 25 58 14 5.06 130 83
Aug. 77 25 57 14 6.06 156 84
Sep. 77 25 56 14 9.71 249 84
Oct. 78 25 57 14 9.78 251 85
Nov. 75 24 57 14 4.31 110 84
Dec. 73 23 56 14 2.28 58 8

Grecia

MonthAverage HighsAverage LowsAverage RainfallHumidity
FCFCin.mm%
Jan. 84 29 63 17 0.29 7 70
Feb. 86 30 64 18 0.48 12 69
Mar. 87 31 65 18 0.58 15 68
Apr. 87 31 65 18 2.7 69 71
May 84 29 65 19 10.07 258 83
Jun. 82 28 65 18 10.83 278 87
Jul. 82 28 65 18 7.56 194 83
Aug. 82 28 64 18 10.49 269 85
Sep. 81 27 64 18 13.12 336 89
Oct. 81 27 64 18 12.79 328 89
Nov. 82 28 64 18 5.69 146 84
Dec. 83 28 64 18 1.23 32 74

Heredia

MonthAverage HighsAverage LowsAverage RainfallHumidity
FCFCin.mm%
Jan. 76 24 59 15 0.78 20 73
Feb. 75 24 57 14 0.96 25 72
Mar. 79 26 58 15 1.91 49 71
Apr. 79 26 59 15 4.86 125 74
May 78 26 61 16 12.49 320 83
Jun. 76 25 59 15 12.88 330 85
Jul. 76 25 60 16 8.03 205 82
Aug. 76 25 60 16 9.73 249 84
Sep. 76 24 59 15 15.55 399 87
Oct. 76 25 59 15 16.42 421 87
Nov. 75 24 60 15 7.02 180 82
Dec. 75 24 60 16 2.14 55 76

Irazu Volcano

MonthAverage HighsAverage LowsAverage RainfallHumidity
FCFCin.mm%
Jan. 52 11 39 4 1.34 34 80
Feb. 52 11 39 4 2.36 60 76
Mar. 64 18 40 4 1.1 28 74
Apr. 54 12 40 4 3.86 98 81
May 53 12 41 5 8.27 210 87
Jun. 51 11 42 6 8.9 226 91
Jul. 50 10 41 5 6.77 172 90
Aug. 51 11 39 4 8.27 210 90
Sep. 51 11 41 5 8.94 227 90
Oct. 51 11 41 5 10.63 270 90
Nov. 61 16 41 5 11.42 290 89
Dec. 51 11 39 4 6.38 162 83

Poas Volcano

MonthAverage HighsAverage LowsAverage RainfallHumidity
FCFCin.mm%
Jan. 69 21 53 12 5.91 150 82
Feb. 89 32 53 12 3.82 97 81
Mar. 71 22 53 12 1.65 42 82
Apr. 71 22 55 13 4.8 122 83
May 71 22 57 14 13.7 348 90
Jun. 71 22 57 14 16.54 420 91
Jul. 69 21 57 14 14.13 359 89
Aug. 69 21 57 14 18.03 458 89
Sep. 71 22 55 13 19.41 493 91
Oct. 59 15 57 14 16.77 426 91
Nov. 58 14 57 14 16.89 429 89
Dec. 59 15 57 14 12.99 330 85

San Jose

MonthAverage HighsAverage LowsAverage RainfallHumidity
FCFCin.mm%
Jan. 73 23 59 15 0.39 10 82
Feb. 75 24 59 15 0.24 6 80
Mar. 77 25 60 16 0.47 12 78
Apr. 78 26 60 16 1.73 44 79
May 78 26 62 17 8.86 225 84
Jun. 78 26 62 17 11.3 287 85
Jul. 77 25 62 17 8.46 215 84
Aug. 77 25 62 17 9.8 249 85
Sep. 76 24 60 16 13.07 332 86
Oct. 77 25 60 16 13.07 332 86
Nov. 75 24 60 16 5.59 142 84
Dec. 73 23 59 15 1.61 41 83

Source: National Weather Services of Costa Rica

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