Kalama
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kalama clear sky chart from 2005-11-06 to 2026-01-02.

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	17% 10% 3 8% 5% 4 4 4 5% 6% 33%	132153
	Night	19% 11% 3 8% 5% 4 4 3 5% 6% 33%	127942
Transparency	Day	32% 37% 8% 12% 8% 2	131875
	Night	34% 38% 7% 12% 7% 1	127797
Seeing	Day	25% 12% 26% 25% 10% 2	16381
	Night	29% 7% 17% 31% 15% 1	24963

By Month

Percentage Cloud Cover NW (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	34% 19% 5% 10% 5% 4 4 3 4 4 9%	3647
	11th to 20th	Day	24% 11% 4 8% 6% 5% 6% 4 5% 6% 22%	3616
	21st to end	Day	24% 13% 4 8% 5% 4 4 3 4 5% 27%	4344
February	1st to 10th	Day	29% 15% 4 9% 5% 5% 4 4 5% 6% 14%	1800
	11th to 20th	Day	30% 15% 6% 10% 6% 4 4 3 3 4 16%	1755
	21st to end	Day	29% 17% 5% 10% 5% 5% 3 3 4 5% 16%	1551
March	1st to 10th	Day	17% 15% 5% 12% 7% 6% 5% 4 6% 6% 16%	4732
	11th to 20th	Day	22% 17% 5% 10% 6% 4 3 3 3 4 23%	5000
	21st to end	Day	24% 17% 5% 13% 7% 6% 5% 4 5% 4 11%	5607
April	1st to 10th	Day	28% 15% 5% 10% 6% 5% 4 4 5% 5% 15%	2400
	11th to 20th	Day	24% 13% 4 9% 5% 4 4 4 4 4 24%	2386
	21st to end	Day	22% 12% 4 9% 7% 5% 5% 4 5% 6% 22%	2600
May	1st to 10th	Day	15% 8% 3 7% 5% 4 4 3 5% 6% 40%	6265
	11th to 20th	Day	14% 10% 4 9% 6% 6% 6% 5% 7% 7% 27%	6277
	21st to end	Day	17% 8% 3 9% 6% 5% 5% 4 6% 8% 30%	6903
June	1st to 10th	Day	21% 10% 4 8% 5% 4 4 4 5% 6% 31%	2800
	11th to 20th	Day	18% 10% 3 9% 6% 6% 6% 4 6% 7% 24%	2883
	21st to end	Day	10% 7% 3 6% 5% 5% 5% 4 6% 7% 42%	3000
July	1st to 10th	Day	3 3 2 4 3 3 3 3 4 5% 67%	6606
	11th to 20th	Day	4 3 1 2 2 2 2 2 4 5% 73%	6320
	21st to end	Day	6% 3 1 3 2 3 3 3 5% 7% 63%	6874
August	1st to 10th	Day	4 4 2 5% 3 3 3 3 5% 7% 62%	4294
	11th to 20th	Day	6% 5% 2 7% 5% 5% 6% 6% 7% 9% 43%	4156
	21st to end	Day	11% 8% 3 6% 4 3 4 3 5% 6% 46%	4455
September	1st to 10th	Day	8% 6% 2 5% 4 4 4 4 6% 7% 51%	2400
	11th to 20th	Day	12% 7% 3 9% 5% 5% 5% 3 5% 7% 40%	2400
	21st to end	Day	16% 7% 2 6% 5% 4 4 3 5% 6% 41%	2103
October	1st to 10th	Day	16% 7% 2 6% 3 3 5% 3 6% 9% 41%	3280
	11th to 20th	Day	18% 9% 4 10% 6% 5% 5% 4 6% 7% 26%	3261
	21st to end	Day	24% 11% 4 9% 7% 5% 5% 4 6% 6% 20%	3466
November	1st to 10th	Day	29% 13% 5% 10% 6% 5% 6% 4 5% 5% 13%	1715
	11th to 20th	Day	33% 13% 4 9% 4 4 5% 3 5% 5% 16%	1680
	21st to end	Day	30% 13% 5% 10% 5% 4 4 3 5% 4 19%	1680
December	1st to 10th	Day	21% 10% 3 8% 5% 5% 5% 3 5% 5% 28%	2700
	11th to 20th	Day	28% 15% 5% 13% 7% 5% 4 3 4 3 10%	3105
	21st to end	Day	29% 18% 5% 12% 7% 5% 5% 3 4 3 9%	4092
January	1st to 10th	Night	32% 17% 5% 11% 5% 5% 4 3 3 3 11%	6320
	11th to 20th	Night	21% 11% 3 8% 5% 5% 5% 4 6% 6% 26%	6282
	21st to end	Night	25% 12% 4 7% 4 3 3 2 4 5% 30%	6622
February	1st to 10th	Night	26% 16% 4 11% 6% 4 5% 4 4 4 16%	2600
	11th to 20th	Night	24% 16% 5% 9% 5% 4 4 3 4 5% 22%	2532
	21st to end	Night	26% 15% 4 10% 5% 5% 3 4 4 4 19%	2078
March	1st to 10th	Night	15% 16% 5% 10% 6% 6% 7% 5% 6% 5% 19%	5160
	11th to 20th	Night	21% 15% 4 9% 5% 4 5% 3 4 4 24%	4999
	21st to end	Night	27% 18% 4 11% 6% 6% 4 3 4 5% 12%	5368
April	1st to 10th	Night	23% 15% 4 10% 6% 5% 4 3 4 5% 22%	2000
	11th to 20th	Night	19% 12% 4 8% 6% 5% 5% 3 5% 6% 28%	1961
	21st to end	Night	21% 11% 3 8% 4 4 4 4 6% 7% 29%	1800
May	1st to 10th	Night	16% 7% 2 6% 3 3 4 3 4 6% 45%	3696
	11th to 20th	Night	12% 9% 3 7% 4 4 5% 4 5% 7% 38%	3616
	21st to end	Night	9% 9% 3 7% 6% 5% 5% 5% 7% 9% 37%	3972
June	1st to 10th	Night	15% 8% 3 8% 5% 4 4 3 4 6% 39%	1600
	11th to 20th	Night	14% 8% 2 6% 5% 4 4 3 5% 9% 41%	1510
	21st to end	Night	8% 5% 2 5% 3 4 3 3 4 7% 57%	1400
July	1st to 10th	Night	2 1 2 2 2 2 2 4 6% 75%	3336
	11th to 20th	Night	2 2 1 2 2 2 2 2 3 4 78%	3640
	21st to end	Night	3 2 1 2 2 2 2 2 5% 7% 72%	3969
August	1st to 10th	Night	2 2 1 3 2 2 2 2 4 6% 74%	2862
	11th to 20th	Night	6% 4 2 4 3 3 4 4 6% 9% 57%	2902
	21st to end	Night	11% 6% 2 5% 4 3 3 3 4 5% 55%	3460
September	1st to 10th	Night	7% 3 1 4 4 3 4 3 4 5% 61%	2000
	11th to 20th	Night	10% 7% 3 7% 5% 4 4 3 5% 6% 47%	2000
	21st to end	Night	11% 5% 2 6% 5% 4 4 3 5% 8% 47%	2293
October	1st to 10th	Night	12% 6% 1 6% 4 4 5% 4 6% 8% 45%	3920
	11th to 20th	Night	18% 8% 3 8% 5% 4 5% 4 6% 8% 32%	3897
	21st to end	Night	21% 10% 4 8% 6% 5% 5% 4 5% 6% 25%	4341
November	1st to 10th	Night	29% 11% 4 9% 5% 5% 5% 3 4 5% 20%	2800
	11th to 20th	Night	32% 12% 3 9% 6% 4 4 3 4 4 19%	2940
	21st to end	Night	27% 13% 3 8% 5% 5% 5% 3 4 5% 22%	2940
December	1st to 10th	Night	18% 10% 4 6% 4 4 6% 5% 6% 6% 30%	4700
	11th to 20th	Night	30% 16% 5% 12% 7% 5% 4 3 4 4 11%	5320
	21st to end	Night	29% 17% 6% 12% 6% 6% 5% 4 3 3 10%	7106

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	60% 26% 5% 5% 3	3647
	11th to 20th	Day	45% 27% 5% 17% 7%	3640
	21st to end	Day	43% 27% 3 12% 11% 3	4344
February	1st to 10th	Day	30% 61% 3 4 1	1800
	11th to 20th	Day	32% 60% 1 3 2 1	1764
	21st to end	Day	29% 61% 3 3 4	1551
March	1st to 10th	Day	47% 29% 11% 8% 5%	4732
	11th to 20th	Day	45% 30% 5% 17% 3	5000
	21st to end	Day	54% 30% 9% 6% 2	5607
April	1st to 10th	Day	28% 62% 5% 5% 1	2400
	11th to 20th	Day	23% 62% 4 7% 4	2386
	21st to end	Day	25% 61% 4 7% 3	2600
May	1st to 10th	Day	32% 28% 8% 21% 11% 1	6265
	11th to 20th	Day	42% 30% 14% 11% 2	6280
	21st to end	Day	36% 30% 18% 13% 3	6904
June	1st to 10th	Day	16% 62% 8% 10% 4	2800
	11th to 20th	Day	20% 61% 6% 9% 3	2883
	21st to end	Day	17% 60% 7% 12% 4	3000
July	1st to 10th	Day	14% 25% 8% 20% 14% 18%	6535
	11th to 20th	Day	8% 25% 8% 17% 35% 6%	6245
	21st to end	Day	20% 26% 13% 26% 14% 1	6681
August	1st to 10th	Day	14% 35% 5% 16% 22% 7%	4277
	11th to 20th	Day	27% 40% 13% 14% 5% 2	4195
	21st to end	Day	26% 36% 7% 14% 13% 4	4454
September	1st to 10th	Day	17% 58% 6% 12% 6% 2	2400
	11th to 20th	Day	20% 57% 5% 7% 8% 2	2400
	21st to end	Day	18% 57% 6% 10% 8% 1	2103
October	1st to 10th	Day	23% 35% 5% 22% 14%	3280
	11th to 20th	Day	38% 37% 7% 10% 8%	3261
	21st to end	Day	43% 37% 6% 9% 5%	3466
November	1st to 10th	Day	34% 54% 4 7% 1	1715
	11th to 20th	Day	32% 55% 4 4 4 1	1680
	21st to end	Day	28% 54% 3 5% 9%	1680
December	1st to 10th	Day	35% 35% 5% 11% 14% 1	2700
	11th to 20th	Day	57% 31% 5% 6% 1	3108
	21st to end	Day	60% 27% 7% 5% 1	4092
January	1st to 10th	Night	60% 26% 5% 5% 4 1	6320
	11th to 20th	Night	41% 28% 4 19% 7%	6320
	21st to end	Night	42% 27% 5% 14% 9% 3	6622
February	1st to 10th	Night	30% 62% 2 4 1	2600
	11th to 20th	Night	30% 61% 2 4 3	2534
	21st to end	Night	25% 62% 5% 6% 3	2078
March	1st to 10th	Night	47% 31% 8% 10% 5%	5160
	11th to 20th	Night	44% 31% 7% 14% 3	5000
	21st to end	Night	55% 30% 7% 7% 1	5368
April	1st to 10th	Night	25% 62% 6% 6% 1	2000
	11th to 20th	Night	20% 62% 6% 8% 5%	1961
	21st to end	Night	22% 61% 6% 9% 2	1800
May	1st to 10th	Night	28% 29% 9% 24% 10%	3693
	11th to 20th	Night	35% 29% 16% 15% 5%	3616
	21st to end	Night	32% 32% 22% 12% 1	3972
June	1st to 10th	Night	16% 61% 8% 12% 4	1600
	11th to 20th	Night	14% 62% 6% 14% 4	1510
	21st to end	Night	13% 60% 9% 15% 3 1	1400
July	1st to 10th	Night	10% 26% 9% 24% 13% 18%	3298
	11th to 20th	Night	8% 25% 6% 22% 34% 6%	3592
	21st to end	Night	13% 28% 17% 27% 14% 1	3857
August	1st to 10th	Night	10% 35% 6% 22% 24% 4	2854
	11th to 20th	Night	24% 40% 16% 13% 4 2	2929
	21st to end	Night	23% 36% 10% 13% 15% 2	3460
September	1st to 10th	Night	15% 56% 8% 13% 6% 2	2000
	11th to 20th	Night	19% 58% 6% 8% 6% 3	2000
	21st to end	Night	17% 57% 7% 12% 7%	2293
October	1st to 10th	Night	22% 37% 6% 22% 13%	3920
	11th to 20th	Night	35% 37% 8% 13% 7%	3897
	21st to end	Night	42% 37% 4 12% 4 1	4341
November	1st to 10th	Night	34% 53% 4 7% 2	2800
	11th to 20th	Night	32% 54% 4 5% 3 2	2940
	21st to end	Night	28% 54% 4 5% 8% 1	2940
December	1st to 10th	Night	31% 35% 6% 14% 14%	4700
	11th to 20th	Night	57% 31% 5% 5% 2	5316
	21st to end	Night	60% 28% 5% 6% 1	7106

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	46% 11% 23% 11% 7% 2	202
	11th to 20th	Day	40% 15% 21% 14% 7% 5%	200
	21st to end	Day	36% 10% 21% 22% 10% 2	365
February	1st to 10th	Day	43% 12% 19% 16% 9% 2	400
	11th to 20th	Day	44% 13% 23% 16% 5% 1	395
	21st to end	Day	40% 15% 23% 15% 7%	365
March	1st to 10th	Day	34% 17% 26% 17% 6%	500
	11th to 20th	Day	35% 14% 23% 17% 9% 3	500
	21st to end	Day	38% 16% 22% 16% 7% 1	550
April	1st to 10th	Day	35% 14% 22% 19% 8% 2	500
	11th to 20th	Day	29% 22% 25% 15% 7% 2	492
	21st to end	Day	27% 15% 29% 21% 7% 1	500
May	1st to 10th	Day	20% 17% 28% 23% 10% 2	503
	11th to 20th	Day	30% 14% 23% 23% 9% 2	528
	21st to end	Day	24% 11% 27% 26% 10% 2	573
June	1st to 10th	Day	25% 11% 26% 28% 9% 1	530
	11th to 20th	Day	22% 18% 35% 20% 5% 1	613
	21st to end	Day	13% 9% 35% 32% 10% 1	730
July	1st to 10th	Day	11% 8% 35% 35% 11% 2	654
	11th to 20th	Day	9% 8% 31% 37% 13% 3	524
	21st to end	Day	6% 5% 30% 39% 18% 2	575
August	1st to 10th	Day	10% 5% 26% 43% 13% 3	527
	11th to 20th	Day	6% 4 25% 40% 20% 5%	517
	21st to end	Day	10% 9% 33% 32% 13% 3	583
September	1st to 10th	Day	13% 6% 31% 35% 13% 2	530
	11th to 20th	Day	18% 9% 24% 32% 15% 2	530
	21st to end	Day	21% 12% 25% 30% 11% 2	530
October	1st to 10th	Day	25% 10% 25% 25% 12% 2	530
	11th to 20th	Day	28% 12% 21% 23% 14% 2	530
	21st to end	Day	32% 17% 21% 17% 10% 2	527
November	1st to 10th	Day	36% 17% 22% 18% 6%	256
	11th to 20th	Day	43% 11% 20% 16% 9% 1	220
	21st to end	Day	33% 17% 22% 13% 14% 1	220
December	1st to 10th	Day	35% 12% 20% 18% 12% 2	220
	11th to 20th	Day	47% 14% 23% 11% 5%	220
	21st to end	Day	44% 12% 22% 13% 8% 1	242
January	1st to 10th	Night	44% 9% 16% 18% 11% 1	804
	11th to 20th	Night	40% 8% 13% 24% 14% 1	800
	21st to end	Night	36% 6% 12% 28% 17% 1	880
February	1st to 10th	Night	38% 8% 13% 28% 12% 1	800
	11th to 20th	Night	35% 9% 16% 27% 13%	784
	21st to end	Night	38% 8% 16% 26% 11%	660
March	1st to 10th	Night	36% 8% 17% 26% 12% 1	800
	11th to 20th	Night	35% 8% 16% 29% 12% 1	800
	21st to end	Night	39% 11% 14% 25% 10% 1	880
April	1st to 10th	Night	33% 9% 19% 25% 13% 1	800
	11th to 20th	Night	27% 9% 21% 30% 12% 2	773
	21st to end	Night	28% 7% 17% 32% 16% 1	600
May	1st to 10th	Night	21% 7% 23% 34% 14% 1	430
	11th to 20th	Night	23% 6% 18% 35% 17% 2	394
	21st to end	Night	17% 5% 21% 37% 19%	433
June	1st to 10th	Night	23% 4 22% 38% 14%	400
	11th to 20th	Night	18% 7% 25% 39% 11% 1	400
	21st to end	Night	12% 3 25% 46% 14%	400
July	1st to 10th	Night	6% 5% 23% 50% 15% 1	390
	11th to 20th	Night	5% 1 30% 51% 13%	388
	21st to end	Night	4 2 21% 56% 16%	438
August	1st to 10th	Night	6% 3 17% 49% 24% 2	547
	11th to 20th	Night	7% 2 13% 44% 31% 2	594
	21st to end	Night	12% 4 20% 43% 19% 1	784
September	1st to 10th	Night	11% 3 21% 44% 19% 2	800
	11th to 20th	Night	17% 5% 17% 33% 27% 3	800
	21st to end	Night	16% 4 21% 39% 19% 2	800
October	1st to 10th	Night	21% 4 15% 38% 19% 2	800
	11th to 20th	Night	28% 4 14% 31% 20% 3	800
	21st to end	Night	32% 6% 17% 27% 16% 1	880
November	1st to 10th	Night	38% 9% 16% 29% 9%	820
	11th to 20th	Night	43% 8% 14% 24% 10% 1	840
	21st to end	Night	35% 8% 15% 25% 14% 2	840
December	1st to 10th	Night	35% 8% 15% 26% 15% 2	840
	11th to 20th	Night	43% 8% 18% 21% 9% 1	840
	21st to end	Night	47% 9% 18% 18% 8% 1	924

Page generated at 2025-12-29 22:14:09. Version ac07

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