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Central Valley Region

Weather > Central Valley Region

Central Valley Region

Written By: Ryan Van Velzer
Last updated: Oct 28, 2023

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

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

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

8

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

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

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

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

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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