Pixie Land
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pixie Land clear sky chart from 2005-11-06 to 2026-01-17.

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	8% 6% 2 6% 4 4 4 4 5% 7% 50%	136538
	Night	10% 7% 3 7% 4 4 4 3 5% 7% 46%	132458
Transparency	Day	34% 7% 12% 24% 17% 7%	131276
	Night	38% 8% 14% 23% 13% 4	128720
Seeing	Day	13% 15% 28% 24% 15% 4	15925
	Night	14% 11% 26% 31% 16% 2	25028

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	21% 17% 6% 17% 6% 6% 5% 3 4 4 10%	3719
	11th to 20th	Day	15% 13% 4 8% 5% 4 4 4 7% 7% 31%	3688
	21st to end	Day	19% 12% 5% 11% 5% 4 4 3 4 5% 28%	4119
February	1st to 10th	Day	14% 14% 4 11% 5% 4 6% 5% 6% 7% 24%	1800
	11th to 20th	Day	14% 10% 3 8% 5% 5% 6% 4 7% 6% 31%	1755
	21st to end	Day	11% 9% 3 8% 7% 5% 6% 4 7% 8% 29%	1642
March	1st to 10th	Day	8% 9% 3 7% 5% 6% 6% 5% 10% 10% 31%	4518
	11th to 20th	Day	9% 9% 3 9% 6% 4 4 4 5% 7% 40%	4973
	21st to end	Day	9% 9% 3 10% 7% 7% 7% 5% 7% 9% 26%	5781
April	1st to 10th	Day	8% 8% 3 8% 5% 6% 6% 5% 7% 9% 35%	2400
	11th to 20th	Day	8% 8% 2 6% 5% 5% 5% 4 7% 8% 41%	2369
	21st to end	Day	5% 5% 2 6% 4 5% 5% 5% 7% 9% 47%	2551
May	1st to 10th	Day	8% 4 1 4 3 4 4 3 5% 7% 56%	6320
	11th to 20th	Day	4 4 2 5% 4 4 4 4 6% 8% 56%	6277
	21st to end	Day	5% 4 1 4 4 4 4 4 6% 9% 54%	6902
June	1st to 10th	Day	8% 5% 2 6% 4 4 4 4 6% 8% 50%	2800
	11th to 20th	Day	4 4 1 5% 4 4 4 4 6% 9% 56%	2800
	21st to end	Day	3 3 2 3 3 3 3 3 4 6% 68%	2800
July	1st to 10th	Day	1 1 1 2 1 1 2 2 3 4 84%	6319
	11th to 20th	Day	1 1 1 1 1 1 2 2 2 3 85%	6320
	21st to end	Day	2 2 1 2 1 2 2 2 3 4 80%	6880
August	1st to 10th	Day	2 3 1 3 2 2 3 3 4 5% 71%	6129
	11th to 20th	Day	1 1 1 3 2 3 3 3 4 6% 72%	5796
	21st to end	Day	4 4 1 5% 3 3 4 3 4 6% 63%	5989
September	1st to 10th	Day	2 2 1 3 2 3 3 3 4 6% 72%	2400
	11th to 20th	Day	4 3 1 4 3 3 4 4 4 7% 61%	2400
	21st to end	Day	7% 3 1 5% 3 3 4 3 5% 6% 58%	2145
October	1st to 10th	Day	5% 3 1 4 3 3 4 3 6% 8% 59%	3280
	11th to 20th	Day	6% 4 3 8% 5% 5% 5% 5% 8% 8% 43%	3261
	21st to end	Day	10% 6% 3 7% 6% 6% 6% 4 7% 9% 36%	3312
November	1st to 10th	Day	14% 12% 3 9% 5% 6% 5% 5% 7% 8% 26%	1833
	11th to 20th	Day	15% 13% 5% 11% 6% 5% 5% 5% 6% 7% 21%	1680
	21st to end	Day	15% 12% 3 11% 7% 5% 5% 4 6% 6% 25%	1680
December	1st to 10th	Day	11% 11% 4 14% 7% 6% 4 4 6% 6% 27%	2700
	11th to 20th	Day	20% 17% 7% 17% 6% 5% 4 3 5% 4 11%	3108
	21st to end	Day	19% 16% 7% 13% 7% 6% 5% 4 5% 6% 11%	4092
January	1st to 10th	Night	21% 18% 7% 17% 6% 4 4 4 4 4 11%	6446
	11th to 20th	Night	17% 11% 3 7% 4 3 3 3 6% 6% 38%	6404
	21st to end	Night	19% 11% 4 10% 5% 4 3 3 4 4 33%	6838
February	1st to 10th	Night	14% 14% 4 8% 5% 4 5% 4 6% 6% 29%	2600
	11th to 20th	Night	13% 11% 4 7% 5% 4 5% 3 5% 7% 36%	2532
	21st to end	Night	12% 12% 3 10% 6% 5% 4 4 5% 7% 33%	1986
March	1st to 10th	Night	7% 8% 2 7% 5% 6% 6% 5% 8% 9% 35%	5376
	11th to 20th	Night	8% 7% 3 8% 5% 5% 5% 4 6% 6% 43%	5011
	21st to end	Night	8% 7% 3 8% 7% 7% 7% 5% 8% 10% 29%	5193
April	1st to 10th	Night	10% 7% 3 7% 5% 4 5% 4 7% 9% 40%	2000
	11th to 20th	Night	8% 6% 2 5% 5% 3 5% 4 6% 8% 49%	1979
	21st to end	Night	7% 4 2 5% 5% 5% 4 4 7% 9% 49%	1844
May	1st to 10th	Night	9% 5% 1 4 3 3 3 2 4 5% 61%	3640
	11th to 20th	Night	4 3 2 4 3 3 3 3 5% 8% 61%	3616
	21st to end	Night	7% 4 1 3 2 2 4 3 6% 8% 59%	3972
June	1st to 10th	Night	8% 5% 2 5% 3 5% 4 3 6% 7% 51%	1600
	11th to 20th	Night	5% 3 1 4 3 3 3 4 5% 8% 61%	1600
	21st to end	Night	2 3 1 4 3 3 3 3 4 5% 69%	1600
July	1st to 10th	Night	1 1 2 2 2 2 2 3 4 82%	3640
	11th to 20th	Night	1 1 1 1 2 2 2 2 3 85%	3640
	21st to end	Night	2 2 1 1 1 1 1 3 6% 82%	3970
August	1st to 10th	Night	3 2 1 3 3 3 3 3 3 6% 70%	3664
	11th to 20th	Night	3 2 1 3 3 3 3 3 4 6% 72%	4052
	21st to end	Night	2 3 1 4 3 3 3 3 5% 6% 66%	5010
September	1st to 10th	Night	2 2 1 3 2 2 3 2 4 6% 73%	2000
	11th to 20th	Night	4 3 1 3 4 3 4 3 4 6% 65%	2000
	21st to end	Night	6% 3 1 3 3 3 3 3 5% 7% 62%	2252
October	1st to 10th	Night	5% 3 1 3 3 2 3 3 5% 7% 64%	3920
	11th to 20th	Night	7% 4 2 6% 4 4 6% 4 7% 9% 46%	3897
	21st to end	Night	9% 6% 2 6% 4 5% 6% 5% 7% 8% 41%	4491
November	1st to 10th	Night	16% 7% 3 8% 5% 5% 6% 4 6% 7% 33%	2683
	11th to 20th	Night	18% 11% 4 8% 5% 5% 5% 4 6% 7% 27%	2940
	21st to end	Night	14% 10% 4 8% 6% 5% 5% 4 6% 7% 31%	2940
December	1st to 10th	Night	10% 8% 4 12% 5% 4 4 4 6% 9% 35%	4700
	11th to 20th	Night	22% 17% 6% 13% 7% 6% 5% 4 4 5% 11%	5316
	21st to end	Night	21% 14% 5% 11% 5% 5% 5% 4 5% 6% 20%	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	76% 7% 7% 9% 2	3719
	11th to 20th	Day	50% 7% 17% 19% 6%	3688
	21st to end	Day	60% 7% 7% 17% 10%	4119
February	1st to 10th	Day	58% 11% 17% 11% 3	1800
	11th to 20th	Day	50% 12% 16% 16% 6%	1764
	21st to end	Day	50% 11% 16% 15% 8%	1642
March	1st to 10th	Day	40% 11% 16% 19% 12%	4518
	11th to 20th	Day	43% 7% 12% 31% 8%	4973
	21st to end	Day	49% 12% 15% 20% 4	5781
April	1st to 10th	Day	41% 10% 18% 22% 9%	2400
	11th to 20th	Day	37% 8% 18% 20% 13% 2	2372
	21st to end	Day	30% 10% 19% 26% 13% 2	2551
May	1st to 10th	Day	27% 5% 10% 24% 29% 4	6320
	11th to 20th	Day	24% 5% 14% 36% 18% 3	6280
	21st to end	Day	24% 9% 20% 34% 12% 1	6904
June	1st to 10th	Day	31% 7% 14% 30% 16% 3	2800
	11th to 20th	Day	23% 6% 15% 35% 18% 3	2800
	21st to end	Day	17% 4 14% 34% 23% 9%	2800
July	1st to 10th	Day	8% 2 5% 23% 33% 30%	6251
	11th to 20th	Day	7% 2 4 15% 33% 40%	6245
	21st to end	Day	11% 2 7% 31% 34% 15%	6681
August	1st to 10th	Day	14% 3 6% 18% 34% 24%	4466
	11th to 20th	Day	13% 3 11% 38% 26% 9%	4195
	21st to end	Day	21% 4 10% 25% 33% 7%	4316
September	1st to 10th	Day	14% 4 9% 32% 28% 13%	2400
	11th to 20th	Day	22% 6% 14% 28% 23% 7%	2400
	21st to end	Day	27% 6% 15% 29% 19% 5%	2145
October	1st to 10th	Day	23% 5% 13% 33% 23% 3	3280
	11th to 20th	Day	36% 7% 19% 23% 14% 1	3261
	21st to end	Day	41% 8% 14% 28% 9% 1	3312
November	1st to 10th	Day	52% 11% 15% 17% 4	1833
	11th to 20th	Day	61% 10% 13% 13% 2 1	1680
	21st to end	Day	58% 9% 17% 10% 5% 1	1680
December	1st to 10th	Day	55% 9% 15% 17% 4	2700
	11th to 20th	Day	75% 8% 9% 7% 2	3108
	21st to end	Day	70% 11% 10% 8% 1	4092
January	1st to 10th	Night	75% 9% 8% 6% 1	6446
	11th to 20th	Night	46% 8% 19% 23% 5%	6404
	21st to end	Night	57% 6% 8% 18% 10%	6838
February	1st to 10th	Night	54% 10% 18% 14% 3	2600
	11th to 20th	Night	46% 10% 17% 19% 6% 1	2534
	21st to end	Night	48% 10% 15% 19% 6% 1	1986
March	1st to 10th	Night	39% 11% 16% 23% 11% 1	5376
	11th to 20th	Night	39% 8% 15% 28% 10%	5011
	21st to end	Night	45% 14% 17% 22% 2	5193
April	1st to 10th	Night	39% 10% 19% 24% 8% 1	2000
	11th to 20th	Night	32% 8% 18% 26% 13% 3	1979
	21st to end	Night	30% 11% 17% 28% 12% 2	1844
May	1st to 10th	Night	25% 5% 9% 26% 32% 2	3637
	11th to 20th	Night	21% 5% 18% 37% 17% 2	3616
	21st to end	Night	21% 9% 28% 32% 10%	3972
June	1st to 10th	Night	31% 8% 14% 33% 11% 3	1600
	11th to 20th	Night	22% 6% 16% 38% 18% 1	1600
	21st to end	Night	18% 4 13% 34% 24% 6%	1600
July	1st to 10th	Night	9% 2 7% 25% 32% 27%	3600
	11th to 20th	Night	7% 2 5% 14% 38% 34%	3592
	21st to end	Night	7% 2 7% 33% 34% 17%	3857
August	1st to 10th	Night	14% 2 5% 20% 36% 23%	2658
	11th to 20th	Night	13% 4 12% 42% 22% 8%	2929
	21st to end	Night	15% 3 14% 28% 30% 10%	3603
September	1st to 10th	Night	13% 4 13% 29% 28% 14%	2000
	11th to 20th	Night	21% 6% 12% 30% 20% 11%	2000
	21st to end	Night	21% 6% 15% 30% 22% 6%	2252
October	1st to 10th	Night	20% 4 12% 33% 28% 2	3920
	11th to 20th	Night	32% 7% 19% 26% 15% 1	3897
	21st to end	Night	36% 8% 14% 29% 12% 1	4491
November	1st to 10th	Night	48% 10% 16% 20% 6%	2683
	11th to 20th	Night	55% 11% 13% 16% 4	2940
	21st to end	Night	52% 10% 17% 15% 6%	2940
December	1st to 10th	Night	45% 10% 16% 25% 4	4700
	11th to 20th	Night	73% 10% 9% 6% 1	5316
	21st to end	Night	64% 11% 12% 10% 3	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	27% 18% 19% 24% 10% 2	220
	11th to 20th	Day	25% 10% 22% 26% 12% 4	212
	21st to end	Day	25% 7% 25% 25% 14% 3	270
February	1st to 10th	Day	22% 16% 28% 23% 10% 2	400
	11th to 20th	Day	26% 17% 25% 23% 10% 1	395
	21st to end	Day	19% 20% 26% 24% 9% 2	411
March	1st to 10th	Day	18% 19% 29% 23% 9% 2	500
	11th to 20th	Day	17% 19% 26% 25% 11% 3	500
	21st to end	Day	19% 20% 32% 19% 10% 1	550
April	1st to 10th	Day	21% 19% 30% 18% 10% 3	500
	11th to 20th	Day	15% 26% 30% 16% 9% 3	492
	21st to end	Day	14% 22% 31% 21% 10% 2	500
May	1st to 10th	Day	14% 18% 30% 23% 12% 3	503
	11th to 20th	Day	16% 16% 31% 21% 12% 4	528
	21st to end	Day	11% 16% 30% 25% 13% 5%	573
June	1st to 10th	Day	11% 21% 27% 22% 14% 5%	530
	11th to 20th	Day	11% 24% 35% 19% 8% 2	530
	21st to end	Day	6% 15% 31% 27% 17% 4	530
July	1st to 10th	Day	3 10% 41% 28% 14% 4	526
	11th to 20th	Day	5% 11% 34% 30% 16% 4	524
	21st to end	Day	2 9% 30% 29% 22% 8%	575
August	1st to 10th	Day	6% 7% 28% 25% 24% 10%	527
	11th to 20th	Day	2 7% 24% 32% 25% 9%	517
	21st to end	Day	7% 11% 27% 23% 23% 9%	583
September	1st to 10th	Day	4 11% 24% 29% 22% 10%	530
	11th to 20th	Day	8% 10% 28% 27% 22% 5%	530
	21st to end	Day	8% 15% 24% 27% 21% 6%	530
October	1st to 10th	Day	10% 14% 28% 23% 17% 7%	530
	11th to 20th	Day	13% 16% 22% 25% 18% 6%	530
	21st to end	Day	17% 14% 26% 23% 15% 4	438
November	1st to 10th	Day	20% 13% 28% 24% 11% 3	319
	11th to 20th	Day	22% 18% 22% 24% 11% 3	220
	21st to end	Day	21% 11% 20% 30% 16% 1	220
December	1st to 10th	Day	25% 12% 20% 25% 13% 6%	220
	11th to 20th	Day	26% 12% 29% 23% 9% 1	220
	21st to end	Day	20% 17% 26% 24% 12% 1	242
January	1st to 10th	Night	26% 10% 24% 28% 11% 1	840
	11th to 20th	Night	23% 8% 21% 30% 16% 2	824
	21st to end	Night	20% 8% 20% 32% 17% 2	880
February	1st to 10th	Night	21% 13% 23% 30% 13% 1	800
	11th to 20th	Night	17% 13% 23% 32% 14% 1	784
	21st to end	Night	18% 17% 23% 32% 11%	660
March	1st to 10th	Night	16% 11% 27% 31% 15% 1	800
	11th to 20th	Night	13% 11% 27% 35% 13% 1	800
	21st to end	Night	14% 17% 32% 26% 10% 1	880
April	1st to 10th	Night	15% 15% 28% 28% 14% 1	800
	11th to 20th	Night	12% 18% 30% 25% 13% 2	791
	21st to end	Night	8% 17% 36% 26% 12% 1	644
May	1st to 10th	Night	9% 16% 31% 28% 16% 1	400
	11th to 20th	Night	10% 11% 28% 32% 17% 2	394
	21st to end	Night	7% 8% 32% 36% 13% 3	433
June	1st to 10th	Night	11% 15% 31% 28% 15% 1	400
	11th to 20th	Night	9% 17% 41% 25% 8%	400
	21st to end	Night	4 13% 32% 34% 17% 1	400
July	1st to 10th	Night	3 9% 32% 37% 18% 1	390
	11th to 20th	Night	1 7% 41% 36% 13% 2	388
	21st to end	Night	2 8% 28% 40% 21% 1	438
August	1st to 10th	Night	2 6% 27% 38% 23% 3	429
	11th to 20th	Night	3 4 21% 35% 27% 10%	594
	21st to end	Night	3 10% 28% 34% 22% 4	875
September	1st to 10th	Night	3 6% 24% 35% 29% 3	800
	11th to 20th	Night	5% 5% 27% 29% 29% 5%	800
	21st to end	Night	7% 8% 22% 31% 29% 4	800
October	1st to 10th	Night	10% 7% 22% 38% 20% 3	800
	11th to 20th	Night	13% 9% 22% 30% 24% 3	800
	21st to end	Night	15% 9% 26% 32% 15% 3	880
November	1st to 10th	Night	18% 10% 23% 36% 13%	820
	11th to 20th	Night	23% 10% 24% 30% 12% 1	840
	21st to end	Night	15% 10% 23% 34% 15% 3	840
December	1st to 10th	Night	19% 9% 24% 29% 17% 2	840
	11th to 20th	Night	25% 8% 22% 32% 12% 1	840
	21st to end	Night	24% 12% 24% 29% 9% 1	924

Page generated at 2026-01-13 22:14:30. Version ac07

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