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Central Valley Weather Region

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Last Updated on Monday, 25 May 2009 14:11


The Central Valley Weather Region includes parts of the provinces of Heredia, San José, Alajuela and Cartago, including popular cites like San Jose, Heredia, Escazu, Santa Ana, Cartago, Barva and Grecia (among many others).

The average annual temperatures are between 22°C (72°F) and 24°C (75°F), and these do not vary much throughout the year. The max usually averages 29°C (84°F) and the lowest averages 18°C (64°). Relative humidity averages about 75%, dropping to 69% during the dry season.

The dry season is December to March, with April and November being months of transition. July tends to be the driest of the wet months and is referred to as “veranillo” (little dry season).

This said, we can summarize and say that the dry season generally extends from December until April. During this time the humidity is lower. This time of year (Jan- March, more specifically) is also marked with persistent NE winds (as high as 30 km/h) and lots of sun (8hrs or more per day).

The rainy season (May through November) is characterized by less sun and lots more rain.  Usually, you get at least 4 hours of sun in the morning (6 a.m. till 10 a.m., or later) before the afternoon storms develop. September and October are typically the rainiest months (averaging 650mm (26 in.) per month) of the year and the most humid.  The humidity never really goes above 80%. The Central Valley region receives 1,967mm (77.4 in) of rain annually.

NOTE: As you ascend into the mountains north of Heredia, especially up past Barva, the weather tends to be cooler and cloudier. You can see the cloud line from Heredia as you look north.   There are considerably more cooler temperatures and more cloud cover in the mountains.

 

 

Alajuela

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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

Source: National Weather Services of Costa Rica

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Cartago

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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 82

Source: National Weather Services of Costa Rica

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Grecia

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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

Source: National Weather Services of Costa Rica

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Heredia

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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

Source: National Weather Services of Costa Rica

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Irazu Volcano

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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

Source: National Weather Services of Costa Rica

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Poas Volcano

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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

Source: National Weather Services of Costa Rica

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San Jose

Month Average Highs Average Lows Average Rainfall Humidity
F C F C in. 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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