Pandale Junction
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pandale Junction clear sky chart from 2005-11-06 to 2026-02-16.

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	9% 5% 2 4 3 3 3 3 4 7% 58%	139840
	Night	9% 4 1 4 3 3 3 3 5% 7% 60%	138378
Transparency	Day	28% 4 9% 22% 21% 16%	134944
	Night	26% 4 9% 21% 22% 17%	134281
Seeing	Day	11% 5% 22% 35% 23% 4	16341
	Night	10% 5% 30% 42% 13% 1	26454

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	7% 6% 1 3 2 2 2 2 3 5% 66%	5365
	11th to 20th	Day	8% 5% 1 4 2 2 3 2 3 5% 65%	5910
	21st to end	Day	14% 7% 2 4 3 3 3 3 4 6% 52%	6468
February	1st to 10th	Day	9% 8% 2 5% 4 4 3 2 4 4 55%	2100
	11th to 20th	Day	11% 6% 3 5% 2 3 2 2 4 6% 55%	1999
	21st to end	Day	9% 5% 2 3 3 2 3 4 4 8% 57%	1650
March	1st to 10th	Day	10% 5% 2 4 3 3 3 3 4 6% 59%	4500
	11th to 20th	Day	14% 5% 2 4 3 2 2 2 3 4 58%	4892
	21st to end	Day	9% 6% 2 5% 3 3 3 3 5% 6% 54%	5464
April	1st to 10th	Day	9% 4 2 5% 3 3 4 3 5% 7% 56%	2390
	11th to 20th	Day	13% 4 2 4 3 2 3 2 5% 6% 56%	2371
	21st to end	Day	13% 5% 2 4 3 3 3 3 4 7% 54%	2400
May	1st to 10th	Day	16% 4 2 5% 3 3 3 3 5% 6% 49%	5596
	11th to 20th	Day	10% 4 1 4 3 3 4 3 5% 7% 57%	5862
	21st to end	Day	13% 5% 2 4 4 4 4 4 6% 9% 46%	6446
June	1st to 10th	Day	5% 3 1 3 3 2 3 4 6% 9% 60%	2600
	11th to 20th	Day	7% 4 1 3 3 3 4 4 5% 7% 59%	2600
	21st to end	Day	7% 4 1 4 4 4 4 4 7% 9% 53%	2600
July	1st to 10th	Day	13% 4 2 4 3 4 4 4 6% 8% 48%	5899
	11th to 20th	Day	5% 3 1 4 3 3 4 4 6% 9% 57%	5838
	21st to end	Day	5% 3 1 4 3 3 4 3 5% 8% 60%	5922
August	1st to 10th	Day	1 1 2 2 2 2 2 4 7% 77%	5348
	11th to 20th	Day	2 1 1 2 2 2 2 3 4 8% 73%	5366
	21st to end	Day	4 2 1 3 3 4 4 4 6% 10% 58%	5984
September	1st to 10th	Day	11% 5% 2 5% 4 5% 5% 5% 5% 8% 45%	2296
	11th to 20th	Day	11% 6% 2 5% 4 4 4 4 5% 8% 46%	2200
	21st to end	Day	9% 4 2 4 3 4 3 3 5% 7% 56%	2200
October	1st to 10th	Day	4 2 1 2 2 2 3 2 4 5% 72%	3590
	11th to 20th	Day	14% 4 2 5% 3 3 2 2 2 4 59%	3568
	21st to end	Day	11% 4 1 3 2 2 2 1 3 4 68%	3685
November	1st to 10th	Day	13% 5% 1 3 2 3 2 2 4 6% 58%	1853
	11th to 20th	Day	10% 4 2 4 3 3 3 2 4 5% 60%	1890
	21st to end	Day	13% 8% 2 4 3 3 3 2 4 5% 53%	1890
December	1st to 10th	Day	20% 9% 3 7% 3 3 2 2 3 4 43%	3030
	11th to 20th	Day	13% 7% 2 6% 3 3 4 3 5% 6% 49%	3481
	21st to end	Day	10% 7% 2 3 2 2 2 1 2 4 65%	4587
January	1st to 10th	Night	7% 4 1 3 3 2 2 2 4 7% 65%	7597
	11th to 20th	Night	7% 5% 1 3 2 2 2 2 3 5% 69%	7080
	21st to end	Night	16% 7% 2 5% 3 3 3 3 4 5% 50%	7746
February	1st to 10th	Night	8% 5% 1 4 3 3 3 3 5% 6% 60%	2520
	11th to 20th	Night	12% 6% 2 4 3 2 3 3 5% 6% 55%	2398
	21st to end	Night	9% 5% 1 4 3 3 3 3 5% 6% 58%	1980
March	1st to 10th	Night	5% 4 1 3 3 3 3 3 6% 7% 61%	5374
	11th to 20th	Night	12% 5% 1 3 2 2 2 3 4 5% 61%	5058
	21st to end	Night	7% 6% 2 4 2 3 3 3 4 5% 60%	5467
April	1st to 10th	Night	7% 4 1 4 3 2 3 3 5% 7% 59%	2005
	11th to 20th	Night	13% 3 1 4 3 3 3 3 4 6% 57%	1977
	21st to end	Night	12% 5% 2 4 3 3 3 2 3 6% 59%	2000
May	1st to 10th	Night	17% 6% 2 5% 4 3 3 2 3 5% 49%	4366
	11th to 20th	Night	7% 3 1 4 3 4 4 4 5% 7% 58%	4053
	21st to end	Night	10% 5% 1 5% 4 3 4 3 7% 9% 48%	4451
June	1st to 10th	Night	3 2 1 3 3 3 4 3 6% 11% 61%	1800
	11th to 20th	Night	4 2 1 3 3 3 4 4 6% 8% 62%	1800
	21st to end	Night	6% 4 1 3 3 3 4 4 6% 8% 57%	1800
July	1st to 10th	Night	9% 3 1 4 4 4 4 4 7% 11% 49%	4080
	11th to 20th	Night	3 2 1 4 2 3 4 3 6% 9% 62%	4123
	21st to end	Night	5% 3 1 4 3 3 4 3 6% 8% 61%	4951
August	1st to 10th	Night	1 1 1 2 1 2 2 3 5% 8% 75%	4464
	11th to 20th	Night	2 1 1 2 2 3 4 3 7% 10% 66%	4483
	21st to end	Night	6% 3 1 4 3 3 4 3 6% 10% 57%	4993
September	1st to 10th	Night	8% 4 2 5% 4 4 4 3 6% 9% 52%	2101
	11th to 20th	Night	9% 4 2 5% 4 3 4 4 6% 9% 50%	2200
	21st to end	Night	7% 3 1 4 4 3 4 3 7% 8% 56%	2200
October	1st to 10th	Night	4 2 1 3 2 2 2 2 3 5% 73%	3590
	11th to 20th	Night	12% 3 1 4 2 2 3 2 3 4 63%	3570
	21st to end	Night	7% 2 1 2 2 2 2 2 2 4 75%	4067
November	1st to 10th	Night	12% 4 1 3 2 3 2 2 3 4 64%	2665
	11th to 20th	Night	7% 4 1 3 2 2 3 3 4 6% 64%	2730
	21st to end	Night	11% 4 1 4 3 3 3 3 5% 5% 58%	2730
December	1st to 10th	Night	22% 8% 2 4 2 3 3 3 4 6% 42%	4380
	11th to 20th	Night	11% 6% 2 5% 3 3 3 3 3 5% 57%	4946
	21st to end	Night	8% 5% 1 3 2 2 2 2 4 6% 65%	6633

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	23% 2 5% 25% 23% 22%	5368
	11th to 20th	Day	25% 2 4 19% 26% 24%	5910
	21st to end	Day	35% 3 4 16% 28% 14%	6468
February	1st to 10th	Day	33% 3 6% 13% 23% 22%	2100
	11th to 20th	Day	31% 4 7% 21% 21% 16%	2009
	21st to end	Day	27% 3 7% 15% 26% 22%	1650
March	1st to 10th	Day	28% 3 5% 16% 17% 31%	4500
	11th to 20th	Day	31% 3 5% 8% 16% 37%	4892
	21st to end	Day	30% 4 7% 15% 20% 23%	5464
April	1st to 10th	Day	29% 4 8% 17% 19% 23%	2390
	11th to 20th	Day	30% 3 9% 19% 18% 20%	2374
	21st to end	Day	32% 4 7% 21% 18% 19%	2400
May	1st to 10th	Day	35% 6% 7% 16% 19% 17%	5596
	11th to 20th	Day	27% 5% 8% 20% 21% 19%	5866
	21st to end	Day	34% 6% 10% 25% 17% 9%	6447
June	1st to 10th	Day	21% 6% 13% 32% 22% 6%	2600
	11th to 20th	Day	24% 5% 11% 25% 27% 8%	2600
	21st to end	Day	26% 7% 15% 27% 19% 6%	2600
July	1st to 10th	Day	33% 6% 18% 29% 14% 1	5836
	11th to 20th	Day	23% 6% 20% 35% 14% 2	5769
	21st to end	Day	21% 5% 19% 27% 24% 4	5752
August	1st to 10th	Day	10% 4 9% 38% 35% 4	3892
	11th to 20th	Day	13% 5% 19% 43% 17% 2	3882
	21st to end	Day	22% 8% 17% 26% 23% 4	4311
September	1st to 10th	Day	36% 7% 11% 22% 16% 8%	2296
	11th to 20th	Day	35% 7% 12% 21% 20% 4	2200
	21st to end	Day	27% 5% 12% 19% 23% 13%	2200
October	1st to 10th	Day	15% 4 7% 15% 22% 36%	3590
	11th to 20th	Day	33% 3 6% 14% 17% 29%	3568
	21st to end	Day	23% 2 4 16% 40% 14%	3685
November	1st to 10th	Day	29% 3 8% 21% 21% 16%	1853
	11th to 20th	Day	27% 5% 7% 20% 21% 20%	1890
	21st to end	Day	34% 3 6% 17% 23% 16%	1890
December	1st to 10th	Day	47% 3 5% 16% 18% 12%	3030
	11th to 20th	Day	35% 5% 8% 17% 20% 15%	3479
	21st to end	Day	26% 2 4 17% 25% 26%	4587
January	1st to 10th	Night	20% 3 6% 21% 31% 19%	7598
	11th to 20th	Night	21% 2 4 16% 28% 30%	7080
	21st to end	Night	38% 4 5% 14% 24% 16%	7746
February	1st to 10th	Night	26% 4 7% 17% 22% 25%	2520
	11th to 20th	Night	31% 4 7% 19% 22% 18%	2398
	21st to end	Night	27% 4 8% 15% 24% 22%	1980
March	1st to 10th	Night	21% 4 9% 20% 22% 25%	5374
	11th to 20th	Night	27% 3 6% 10% 17% 37%	5058
	21st to end	Night	27% 4 9% 18% 19% 23%	5467
April	1st to 10th	Night	25% 5% 10% 19% 18% 23%	2005
	11th to 20th	Night	29% 4 8% 20% 17% 21%	1977
	21st to end	Night	29% 3 10% 22% 20% 16%	2000
May	1st to 10th	Night	38% 4 8% 18% 16% 15%	4363
	11th to 20th	Night	25% 4 11% 18% 23% 18%	4054
	21st to end	Night	31% 6% 13% 25% 16% 9%	4452
June	1st to 10th	Night	17% 7% 15% 34% 23% 5%	1800
	11th to 20th	Night	19% 5% 13% 28% 24% 10%	1800
	21st to end	Night	24% 6% 13% 27% 22% 8%	1800
July	1st to 10th	Night	30% 6% 19% 31% 12% 1	4035
	11th to 20th	Night	19% 7% 18% 36% 17% 3	4069
	21st to end	Night	21% 6% 18% 28% 25% 2	4808
August	1st to 10th	Night	10% 5% 10% 36% 36% 3	3244
	11th to 20th	Night	15% 6% 19% 43% 15% 2	3243
	21st to end	Night	23% 7% 16% 26% 24% 3	3597
September	1st to 10th	Night	29% 6% 15% 22% 18% 10%	2101
	11th to 20th	Night	30% 7% 17% 22% 19% 6%	2200
	21st to end	Night	24% 6% 12% 25% 17% 16%	2200
October	1st to 10th	Night	16% 4 7% 15% 21% 37%	3590
	11th to 20th	Night	27% 3 6% 14% 20% 30%	3570
	21st to end	Night	17% 2 5% 18% 41% 17%	4067
November	1st to 10th	Night	26% 2 7% 20% 27% 18%	2665
	11th to 20th	Night	22% 4 9% 22% 23% 20%	2730
	21st to end	Night	29% 4 7% 21% 21% 19%	2730
December	1st to 10th	Night	44% 3 7% 16% 14% 16%	4380
	11th to 20th	Night	31% 3 7% 19% 23% 17%	4947
	21st to end	Night	22% 3 5% 23% 26% 21%	6633

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	13% 8% 32% 31% 14% 1	330
	11th to 20th	Day	13% 9% 31% 34% 12% 1	330
	21st to end	Day	15% 6% 37% 29% 12% 1	363
February	1st to 10th	Day	17% 8% 27% 29% 16% 4	330
	11th to 20th	Day	17% 8% 36% 28% 9% 1	315
	21st to end	Day	16% 8% 38% 31% 7%	249
March	1st to 10th	Day	17% 9% 39% 28% 7%	300
	11th to 20th	Day	14% 11% 36% 27% 11%	300
	21st to end	Day	11% 13% 38% 30% 6% 1	330
April	1st to 10th	Day	8% 14% 39% 31% 7% 1	490
	11th to 20th	Day	10% 13% 44% 29% 5%	492
	21st to end	Day	12% 11% 41% 28% 7% 1	500
May	1st to 10th	Day	12% 8% 35% 37% 8%	568
	11th to 20th	Day	15% 6% 33% 34% 10% 1	725
	21st to end	Day	16% 6% 31% 38% 8% 1	789
June	1st to 10th	Day	6% 3 20% 49% 19% 3	730
	11th to 20th	Day	8% 2 23% 47% 18% 3	730
	21st to end	Day	6% 2 14% 45% 27% 6%	730
July	1st to 10th	Day	10% 2 7% 40% 35% 6%	721
	11th to 20th	Day	4 1 6% 43% 41% 5%	695
	21st to end	Day	2 5% 43% 43% 7%	575
August	1st to 10th	Day	1 5% 37% 48% 9%	527
	11th to 20th	Day	5% 4 35% 45% 10%	517
	21st to end	Day	3 1 4 32% 48% 12%	583
September	1st to 10th	Day	9% 2 8% 28% 40% 13%	426
	11th to 20th	Day	7% 2 5% 32% 38% 17%	330
	21st to end	Day	11% 2 5% 29% 39% 14%	330
October	1st to 10th	Day	7% 2 11% 35% 39% 6%	330
	11th to 20th	Day	15% 3 12% 39% 27% 5%	330
	21st to end	Day	15% 6% 23% 32% 21% 4	363
November	1st to 10th	Day	18% 5% 21% 32% 21% 4	330
	11th to 20th	Day	16% 8% 17% 32% 19% 8%	330
	21st to end	Day	18% 9% 27% 28% 14% 3	330
December	1st to 10th	Day	16% 7% 24% 29% 19% 4	330
	11th to 20th	Day	14% 8% 32% 24% 18% 3	330
	21st to end	Day	18% 6% 23% 30% 21% 2	363
January	1st to 10th	Night	10% 5% 31% 44% 8%	1039
	11th to 20th	Night	13% 6% 29% 45% 7%	840
	21st to end	Night	14% 8% 35% 36% 7%	924
February	1st to 10th	Night	12% 6% 37% 37% 8%	840
	11th to 20th	Night	15% 8% 40% 31% 5%	804
	21st to end	Night	11% 7% 47% 33% 1	660
March	1st to 10th	Night	15% 9% 44% 29% 3	800
	11th to 20th	Night	13% 11% 41% 31% 4	639
	21st to end	Night	10% 10% 52% 24% 4	660
April	1st to 10th	Night	7% 9% 53% 28% 2	600
	11th to 20th	Night	14% 9% 51% 25% 1	593
	21st to end	Night	9% 12% 53% 22% 4	600
May	1st to 10th	Night	10% 8% 49% 30% 4	600
	11th to 20th	Night	10% 5% 41% 38% 5%	591
	21st to end	Night	10% 6% 45% 33% 6%	650
June	1st to 10th	Night	2 3 34% 54% 6%	600
	11th to 20th	Night	4 1 37% 50% 8%	600
	21st to end	Night	5% 2 26% 50% 16% 1	600
July	1st to 10th	Night	8% 3 11% 58% 18% 2	585
	11th to 20th	Night	3 2 12% 59% 23%	582
	21st to end	Night	3 1 11% 59% 25% 1	657
August	1st to 10th	Night	2 1 7% 62% 28% 2	597
	11th to 20th	Night	5% 1 7% 55% 32% 1	594
	21st to end	Night	5% 1 8% 52% 32% 2	660
September	1st to 10th	Night	8% 2 5% 49% 33% 4	600
	11th to 20th	Night	9% 1 8% 45% 35% 2	600
	21st to end	Night	8% 1 12% 48% 30% 1	600
October	1st to 10th	Night	6% 1 19% 51% 22% 1	600
	11th to 20th	Night	11% 3 25% 48% 14%	600
	21st to end	Night	9% 6% 25% 43% 15% 1	759
November	1st to 10th	Night	13% 4 23% 43% 17% 1	1025
	11th to 20th	Night	9% 4 29% 42% 15% 1	1050
	21st to end	Night	13% 4 31% 40% 12%	1050
December	1st to 10th	Night	15% 5% 24% 43% 13% 1	1050
	11th to 20th	Night	15% 7% 30% 40% 9%	1050
	21st to end	Night	12% 5% 33% 40% 9%	1155

Page generated at 2026-02-13 00:42:13. Version ac07

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