Carmel
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carmel clear sky chart from 2005-11-06 to 2025-09-19.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	6% 6% 2 5% 3 3 4 3 7% 10% 50%	134544
	Night	8% 10% 3 8% 4 3 3 3 5% 8% 45%	131985
Transparency	Day	33% 5% 10% 18% 22% 13%	129501
	Night	37% 6% 8% 16% 20% 13%	128011
Seeing	Day	9% 6% 18% 32% 29% 7%	16685
	Night	12% 4 13% 28% 32% 11%	26086

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 7% 2 5% 3 3 3 3 4 7% 51%	4005
	11th to 20th	Day	9% 6% 2 6% 3 4 4 3 4 5% 54%	4100
	21st to end	Day	13% 8% 3 7% 5% 4 4 3 5% 7% 40%	4510
February	1st to 10th	Day	15% 7% 2 4 4 4 5% 4 5% 6% 45%	1800
	11th to 20th	Day	12% 8% 3 5% 4 4 4 4 5% 7% 43%	1886
	21st to end	Day	11% 8% 3 6% 5% 4 4 3 5% 6% 45%	1650
March	1st to 10th	Day	13% 10% 3 8% 5% 6% 6% 5% 7% 8% 30%	4864
	11th to 20th	Day	10% 7% 2 7% 4 4 4 3 5% 7% 48%	5000
	21st to end	Day	10% 10% 3 6% 4 4 6% 5% 7% 10% 35%	5573
April	1st to 10th	Day	11% 8% 3 5% 4 3 4 4 6% 9% 44%	2400
	11th to 20th	Day	8% 9% 2 5% 4 3 3 3 5% 9% 47%	2369
	21st to end	Day	8% 10% 2 5% 3 3 3 4 5% 9% 49%	2400
May	1st to 10th	Day	6% 5% 1 3 3 2 2 2 4 8% 64%	5455
	11th to 20th	Day	4 6% 2 4 3 2 2 3 5% 9% 59%	5874
	21st to end	Day	4 12% 4 6% 3 3 4 4 6% 9% 44%	6902
June	1st to 10th	Day	6% 7% 2 6% 4 3 4 4 6% 11% 48%	2800
	11th to 20th	Day	3 4 1 3 3 2 3 3 6% 12% 59%	2800
	21st to end	Day	3 5% 2 5% 2 2 3 2 6% 11% 58%	2800
July	1st to 10th	Day	1 3 1 3 2 2 2 3 7% 11% 66%	6194
	11th to 20th	Day	1 2 2 4 2 3 3 4 12% 14% 52%	5880
	21st to end	Day	11% 5% 8% 4 4 4 4 11% 13% 35%	6402
August	1st to 10th	Day	1 4 2 6% 2 3 4 5% 14% 14% 43%	5777
	11th to 20th	Day	3 3 2 3 2 2 3 3 10% 13% 56%	5412
	21st to end	Day	1 3 1 4 3 3 3 3 10% 12% 58%	5984
September	1st to 10th	Day	2 4 1 3 2 2 3 2 4 10% 67%	2400
	11th to 20th	Day	4 7% 2 5% 3 2 3 2 5% 13% 54%	2377
	21st to end	Day	3 3 1 3 2 2 3 3 5% 8% 67%	2026
October	1st to 10th	Day	2 3 1 3 2 2 2 2 5% 8% 69%	3180
	11th to 20th	Day	3 6% 4 6% 3 3 4 3 5% 7% 58%	3161
	21st to end	Day	4 4 2 4 3 4 4 3 5% 8% 59%	3448
November	1st to 10th	Day	7% 4 1 4 4 3 4 3 4 8% 56%	1950
	11th to 20th	Day	7% 7% 1 5% 3 3 4 3 6% 8% 53%	1800
	21st to end	Day	11% 4 2 5% 3 3 4 3 5% 8% 52%	1713
December	1st to 10th	Day	6% 4 2 5% 4 4 4 3 6% 9% 53%	2620
	11th to 20th	Day	15% 9% 2 6% 4 4 5% 4 5% 7% 39%	3028
	21st to end	Day	18% 10% 3 6% 5% 5% 5% 3 6% 7% 33%	4004
January	1st to 10th	Night	9% 8% 3 6% 3 3 3 3 5% 8% 50%	5941
	11th to 20th	Night	9% 7% 2 7% 4 4 4 3 5% 6% 49%	5880
	21st to end	Night	14% 11% 3 8% 4 3 3 3 4 6% 40%	6468
February	1st to 10th	Night	14% 9% 2 6% 4 4 3 3 4 6% 46%	2600
	11th to 20th	Night	12% 10% 2 7% 5% 4 4 4 5% 7% 40%	2402
	21st to end	Night	12% 9% 3 6% 4 4 3 3 5% 6% 46%	1980
March	1st to 10th	Night	17% 16% 3 8% 5% 5% 4 3 5% 5% 30%	5026
	11th to 20th	Night	11% 10% 3 7% 4 4 4 3 4 7% 44%	5000
	21st to end	Night	14% 14% 4 9% 4 4 4 3 5% 7% 33%	5389
April	1st to 10th	Night	10% 10% 2 7% 4 4 4 4 5% 7% 42%	2000
	11th to 20th	Night	10% 10% 2 8% 4 4 4 3 4 8% 46%	1979
	21st to end	Night	8% 10% 2 6% 3 2 3 4 6% 9% 46%	2000
May	1st to 10th	Night	5% 10% 3 10% 3 2 2 1 3 5% 56%	4527
	11th to 20th	Night	4 14% 3 10% 4 3 2 2 4 11% 42%	4036
	21st to end	Night	4 16% 6% 11% 4 2 2 2 2 5% 46%	3972
June	1st to 10th	Night	6% 13% 2 6% 4 3 3 4 4 8% 46%	1600
	11th to 20th	Night	2 7% 3 6% 4 4 3 3 5% 7% 56%	1600
	21st to end	Night	1 8% 3 6% 4 3 4 2 4 11% 54%	1600
July	1st to 10th	Night	4 3 9% 5% 5% 3 2 7% 12% 51%	3766
	11th to 20th	Night	1 6% 6% 11% 4 3 3 4 11% 12% 40%	4100
	21st to end	Night	1 30% 9% 14% 3 3 2 2 4 7% 25%	4472
August	1st to 10th	Night	2 11% 4 13% 6% 4 4 3 10% 12% 31%	4035
	11th to 20th	Night	1 11% 2 10% 4 4 3 1 7% 8% 48%	4454
	21st to end	Night	1 7% 2 9% 4 3 3 3 7% 9% 51%	5015
September	1st to 10th	Night	3 6% 2 5% 4 3 3 2 5% 8% 59%	2000
	11th to 20th	Night	5% 8% 3 7% 4 3 3 2 4 10% 52%	1980
	21st to end	Night	3 4 2 5% 3 2 2 2 3 8% 66%	2147
October	1st to 10th	Night	4 3 1 3 2 2 3 2 4 7% 69%	3800
	11th to 20th	Night	3 12% 4 8% 4 3 3 2 4 5% 51%	3777
	21st to end	Night	5% 8% 2 6% 3 2 3 2 4 7% 58%	4121
November	1st to 10th	Night	8% 6% 2 5% 3 3 3 3 4 9% 55%	2345
	11th to 20th	Night	8% 6% 2 5% 3 3 3 3 6% 8% 52%	2600
	21st to end	Night	9% 5% 2 5% 3 4 3 4 5% 6% 55%	2685
December	1st to 10th	Night	6% 5% 1 4 3 4 4 3 5% 7% 57%	4560
	11th to 20th	Night	14% 9% 3 6% 5% 4 5% 5% 8% 8% 33%	5176
	21st to end	Night	16% 10% 3 10% 6% 5% 5% 4 5% 7% 29%	6952

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	31% 7% 16% 24% 16% 5%	4005
	11th to 20th	Day	34% 5% 9% 13% 20% 20%	4100
	21st to end	Day	43% 6% 7% 11% 19% 14%	4510
February	1st to 10th	Day	38% 7% 9% 17% 18% 11%	1800
	11th to 20th	Day	39% 7% 12% 17% 18% 7%	1895
	21st to end	Day	38% 8% 9% 22% 17% 6%	1650
March	1st to 10th	Day	46% 10% 10% 14% 17% 2	4864
	11th to 20th	Day	35% 5% 13% 27% 12% 8%	5000
	21st to end	Day	39% 11% 16% 23% 10% 1	5573
April	1st to 10th	Day	36% 8% 14% 23% 16% 4	2400
	11th to 20th	Day	35% 7% 12% 23% 17% 6%	2372
	21st to end	Day	30% 8% 16% 25% 17% 4	2400
May	1st to 10th	Day	21% 4 8% 26% 30% 10%	5455
	11th to 20th	Day	21% 2 16% 28% 25% 7%	5877
	21st to end	Day	34% 5% 11% 21% 25% 4	6904
June	1st to 10th	Day	33% 7% 13% 20% 21% 6%	2800
	11th to 20th	Day	22% 4 14% 23% 25% 12%	2800
	21st to end	Day	24% 3 10% 18% 26% 20%	2800
July	1st to 10th	Day	23% 2 4 9% 22% 40%	6128
	11th to 20th	Day	33% 3 5% 8% 23% 28%	5811
	21st to end	Day	53% 1 5% 14% 14% 11%	6217
August	1st to 10th	Day	47% 2 5% 12% 23% 12%	4206
	11th to 20th	Day	29% 2 7% 13% 34% 17%	3916
	21st to end	Day	26% 1 7% 17% 31% 18%	4311
September	1st to 10th	Day	19% 2 7% 16% 26% 30%	2400
	11th to 20th	Day	26% 3 12% 23% 24% 12%	2377
	21st to end	Day	17% 3 12% 20% 32% 16%	2026
October	1st to 10th	Day	17% 3 6% 11% 27% 36%	3180
	11th to 20th	Day	31% 2 8% 18% 25% 15%	3161
	21st to end	Day	24% 3 7% 22% 27% 17%	3448
November	1st to 10th	Day	26% 7% 11% 23% 21% 11%	1950
	11th to 20th	Day	30% 6% 14% 18% 23% 10%	1800
	21st to end	Day	31% 5% 10% 16% 26% 13%	1713
December	1st to 10th	Day	28% 5% 7% 19% 32% 9%	2620
	11th to 20th	Day	45% 5% 11% 17% 15% 8%	3028
	21st to end	Day	49% 7% 13% 18% 10% 3	4004
January	1st to 10th	Night	31% 8% 16% 23% 18% 4	5941
	11th to 20th	Night	36% 7% 10% 13% 21% 13%	5880
	21st to end	Night	45% 6% 6% 10% 19% 15%	6468
February	1st to 10th	Night	39% 6% 9% 15% 18% 13%	2600
	11th to 20th	Night	41% 7% 10% 15% 19% 7%	2403
	21st to end	Night	37% 9% 10% 24% 14% 7%	1980
March	1st to 10th	Night	54% 8% 7% 14% 14% 2	5026
	11th to 20th	Night	37% 6% 13% 20% 17% 8%	5000
	21st to end	Night	45% 10% 13% 19% 10% 3	5389
April	1st to 10th	Night	37% 10% 13% 21% 15% 5%	2000
	11th to 20th	Night	36% 7% 12% 23% 15% 7%	1979
	21st to end	Night	32% 9% 13% 24% 17% 6%	2000
May	1st to 10th	Night	25% 11% 6% 22% 26% 10%	4524
	11th to 20th	Night	28% 3 19% 21% 21% 9%	4037
	21st to end	Night	34% 8% 7% 18% 27% 6%	3972
June	1st to 10th	Night	36% 7% 10% 19% 20% 9%	1600
	11th to 20th	Night	27% 4 11% 14% 26% 19%	1600
	21st to end	Night	25% 3 5% 17% 25% 25%	1600
July	1st to 10th	Night	27% 7% 2 8% 17% 38%	3724
	11th to 20th	Night	47% 2 3 7% 12% 29%	4046
	21st to end	Night	63% 2 3 9% 11% 12%	4345
August	1st to 10th	Night	61% 3 3 7% 12% 15%	2929
	11th to 20th	Night	31% 1 4 8% 34% 23%	3217
	21st to end	Night	32% 1 5% 10% 30% 22%	3608
September	1st to 10th	Night	23% 1 6% 13% 23% 33%	2000
	11th to 20th	Night	30% 3 7% 19% 25% 16%	1980
	21st to end	Night	18% 4 8% 20% 31% 20%	2147
October	1st to 10th	Night	18% 2 6% 12% 24% 38%	3800
	11th to 20th	Night	36% 3 5% 18% 22% 16%	3777
	21st to end	Night	26% 3 6% 21% 26% 18%	4121
November	1st to 10th	Night	31% 5% 9% 20% 21% 14%	2345
	11th to 20th	Night	32% 5% 12% 19% 21% 10%	2600
	21st to end	Night	30% 6% 9% 19% 21% 16%	2685
December	1st to 10th	Night	27% 4 6% 22% 29% 12%	4560
	11th to 20th	Night	48% 5% 10% 14% 17% 7%	5176
	21st to end	Night	52% 9% 12% 15% 8% 4	6952

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	21% 9% 21% 27% 18% 4	358
	11th to 20th	Day	13% 7% 20% 32% 26% 3	400
	21st to end	Day	13% 6% 21% 30% 25% 5%	440
February	1st to 10th	Day	15% 13% 19% 26% 21% 7%	400
	11th to 20th	Day	15% 12% 23% 31% 19% 1	462
	21st to end	Day	9% 11% 25% 36% 18% 2	414
March	1st to 10th	Day	17% 12% 23% 33% 13% 2	500
	11th to 20th	Day	16% 10% 22% 30% 18% 4	500
	21st to end	Day	12% 12% 27% 31% 15% 2	550
April	1st to 10th	Day	15% 8% 24% 31% 19% 3	500
	11th to 20th	Day	10% 9% 27% 30% 20% 3	492
	21st to end	Day	8% 8% 28% 28% 21% 6%	500
May	1st to 10th	Day	9% 8% 24% 30% 24% 5%	503
	11th to 20th	Day	13% 5% 23% 31% 22% 6%	528
	21st to end	Day	15% 5% 19% 31% 23% 6%	573
June	1st to 10th	Day	6% 5% 17% 40% 24% 8%	530
	11th to 20th	Day	4 4 25% 35% 29% 3	530
	21st to end	Day	5% 2 13% 38% 35% 6%	530
July	1st to 10th	Day	6% 2 14% 35% 38% 6%	526
	11th to 20th	Day	5% 6% 30% 48% 10%	524
	21st to end	Day	9% 1 6% 35% 40% 10%	575
August	1st to 10th	Day	8% 2 11% 37% 35% 6%	527
	11th to 20th	Day	6% 1 9% 36% 38% 9%	517
	21st to end	Day	3 2 11% 33% 43% 9%	583
September	1st to 10th	Day	7% 1 12% 30% 39% 11%	530
	11th to 20th	Day	9% 3 13% 34% 33% 8%	523
	21st to end	Day	3 3 12% 29% 42% 10%	490
October	1st to 10th	Day	3 3 15% 31% 39% 9%	490
	11th to 20th	Day	7% 5% 12% 28% 33% 14%	490
	21st to end	Day	7% 3 14% 31% 33% 11%	539
November	1st to 10th	Day	6% 5% 19% 27% 33% 11%	486
	11th to 20th	Day	9% 7% 15% 30% 29% 11%	300
	21st to end	Day	9% 5% 20% 28% 31% 7%	255
December	1st to 10th	Day	13% 5% 23% 24% 28% 9%	200
	11th to 20th	Day	13% 7% 23% 24% 25% 9%	200
	21st to end	Day	16% 12% 23% 27% 17% 5%	220
January	1st to 10th	Night	16% 6% 14% 33% 24% 6%	800
	11th to 20th	Night	12% 5% 15% 31% 28% 9%	800
	21st to end	Night	17% 6% 11% 32% 30% 5%	880
February	1st to 10th	Night	17% 6% 18% 27% 25% 8%	800
	11th to 20th	Night	16% 8% 16% 31% 24% 6%	784
	21st to end	Night	14% 8% 18% 32% 25% 3	660
March	1st to 10th	Night	19% 8% 17% 29% 23% 5%	800
	11th to 20th	Night	16% 7% 15% 30% 26% 6%	800
	21st to end	Night	14% 8% 19% 29% 25% 4	880
April	1st to 10th	Night	13% 6% 18% 29% 29% 6%	800
	11th to 20th	Night	13% 9% 16% 28% 27% 7%	791
	21st to end	Night	10% 6% 16% 31% 28% 10%	800
May	1st to 10th	Night	10% 5% 15% 32% 30% 9%	793
	11th to 20th	Night	14% 4 13% 23% 34% 12%	580
	21st to end	Night	15% 3 15% 29% 26% 12%	433
June	1st to 10th	Night	11% 2 12% 30% 35% 11%	400
	11th to 20th	Night	6% 2 17% 29% 39% 7%	400
	21st to end	Night	6% 2 8% 23% 44% 17%	400
July	1st to 10th	Night	5% 2 10% 24% 43% 17%	436
	11th to 20th	Night	7% 1 7% 14% 42% 29%	582
	21st to end	Night	15% 8% 19% 38% 19%	657
August	1st to 10th	Night	13% 1 11% 21% 39% 15%	597
	11th to 20th	Night	8% 1 8% 24% 41% 18%	765
	21st to end	Night	8% 1 8% 19% 44% 20%	880
September	1st to 10th	Night	7% 1 5% 19% 49% 21%	800
	11th to 20th	Night	10% 1 8% 24% 42% 15%	792
	21st to end	Night	5% 1 6% 21% 43% 23%	760
October	1st to 10th	Night	8% 2 6% 30% 39% 16%	760
	11th to 20th	Night	7% 3 11% 24% 38% 17%	760
	21st to end	Night	7% 4 8% 28% 34% 19%	836
November	1st to 10th	Night	10% 3 11% 30% 36% 11%	780
	11th to 20th	Night	11% 3 11% 30% 37% 8%	800
	21st to end	Night	10% 3 12% 37% 30% 7%	800
December	1st to 10th	Night	13% 5% 14% 36% 26% 6%	800
	11th to 20th	Night	17% 6% 16% 32% 24% 5%	800
	21st to end	Night	18% 7% 19% 32% 20% 4	880

Page generated at 2025-09-15 22:49:16. Version ac07

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