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 2024-01-15.

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	10% 4 2 4 3 2 3 4 5% 7% 55%	74822
	Night	9% 4 2 3 3 2 3 4 5% 7% 58%	74970
Transparency	Day	29% 5% 10% 22% 22% 13%	74562
	Night	26% 5% 10% 21% 22% 15%	74753
Seeing	Day	11% 5% 21% 36% 23% 4	13591
	Night	10% 5% 29% 42% 13% 1	23718

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	10% 6% 2 4 3 2 3 3 3 6% 59%	1730
	11th to 20th	Day	12% 6% 2 4 3 2 3 3 4 5% 57%	1840
	21st to end	Day	10% 6% 2 4 3 2 3 4 4 5% 57%	1980
February	1st to 10th	Day	9% 7% 2 4 4 2 3 3 4 4 56%	1800
	11th to 20th	Day	12% 6% 2 4 3 3 3 3 4 5% 54%	1749
	21st to end	Day	10% 5% 2 3 3 1 3 4 4 8% 58%	1480
March	1st to 10th	Day	13% 7% 3 4 4 2 3 3 3 6% 52%	1800
	11th to 20th	Day	13% 5% 3 5% 4 2 3 4 4 6% 50%	1944
	21st to end	Day	12% 5% 1 3 3 1 2 3 4 6% 59%	2178
April	1st to 10th	Day	10% 3 3 4 4 2 4 3 4 8% 55%	2150
	11th to 20th	Day	13% 3 2 3 4 1 2 3 5% 6% 58%	2131
	21st to end	Day	13% 4 2 3 3 2 3 3 4 6% 56%	2160
May	1st to 10th	Day	14% 4 2 4 4 2 3 4 5% 8% 51%	2218
	11th to 20th	Day	13% 5% 2 4 3 3 4 4 6% 9% 48%	2302
	21st to end	Day	16% 6% 2 4 4 3 4 4 5% 8% 44%	2531
June	1st to 10th	Day	5% 3 1 3 3 2 3 4 6% 8% 61%	2340
	11th to 20th	Day	8% 4 1 3 3 2 4 4 5% 7% 59%	2340
	21st to end	Day	7% 3 2 4 4 3 4 5% 6% 10% 52%	2340
July	1st to 10th	Day	11% 4 2 5% 5% 3 5% 6% 6% 8% 45%	2340
	11th to 20th	Day	6% 2 1 2 2 2 3 5% 5% 7% 65%	2320
	21st to end	Day	4 2 1 2 3 2 4 5% 6% 10% 62%	2349
August	1st to 10th	Day	2 2 1 2 3 2 3 3 4 8% 70%	2149
	11th to 20th	Day	4 2 2 2 4 2 4 5% 6% 11% 57%	2123
	21st to end	Day	6% 3 2 4 5% 3 5% 6% 6% 9% 52%	2376
September	1st to 10th	Day	10% 4 2 4 5% 3 5% 6% 5% 9% 46%	2067
	11th to 20th	Day	12% 6% 2 5% 4 3 4 5% 5% 8% 46%	1980
	21st to end	Day	9% 4 2 4 4 3 4 3 5% 7% 55%	1980
October	1st to 10th	Day	7% 3 2 3 4 2 4 4 5% 7% 58%	1980
	11th to 20th	Day	14% 4 2 4 3 3 3 4 4 5% 54%	1980
	21st to end	Day	13% 4 1 3 3 2 2 2 3 5% 63%	2066
November	1st to 10th	Day	14% 5% 1 3 2 2 3 3 4 6% 56%	1673
	11th to 20th	Day	9% 5% 3 4 4 2 3 3 4 5% 58%	1710
	21st to end	Day	13% 8% 2 4 3 2 3 3 4 5% 54%	1710
December	1st to 10th	Day	15% 6% 3 4 3 1 3 4 4 6% 53%	1710
	11th to 20th	Day	13% 6% 2 4 4 2 4 4 5% 6% 51%	2161
	21st to end	Day	13% 6% 2 3 2 1 2 2 3 5% 60%	3135
January	1st to 10th	Night	9% 5% 2 3 4 2 3 3 4 6% 59%	2449
	11th to 20th	Night	12% 6% 2 3 3 2 4 3 4 7% 56%	2208
	21st to end	Night	12% 5% 2 5% 3 2 3 4 4 5% 55%	2376
February	1st to 10th	Night	8% 6% 2 4 3 2 2 3 5% 6% 59%	2160
	11th to 20th	Night	13% 5% 2 4 3 2 3 3 5% 6% 55%	2098
	21st to end	Night	9% 4 1 3 4 3 3 4 4 7% 57%	1776
March	1st to 10th	Night	11% 5% 2 4 3 2 3 4 5% 7% 54%	2160
	11th to 20th	Night	12% 5% 2 4 4 2 2 5% 5% 5% 54%	2016
	21st to end	Night	9% 3 2 3 3 2 3 3 4 6% 61%	2178
April	1st to 10th	Night	7% 4 2 4 3 1 3 3 5% 7% 59%	1805
	11th to 20th	Night	13% 3 1 3 4 2 3 3 4 6% 57%	1777
	21st to end	Night	11% 4 1 4 3 2 3 3 3 6% 61%	1800
May	1st to 10th	Night	9% 5% 2 3 5% 3 4 4 4 6% 55%	1738
	11th to 20th	Night	11% 5% 2 5% 3 3 4 5% 5% 8% 50%	1593
	21st to end	Night	11% 4 1 4 4 3 4 4 6% 10% 48%	1745
June	1st to 10th	Night	3 2 1 2 3 2 3 5% 5% 11% 64%	1620
	11th to 20th	Night	3 2 1 3 3 3 4 4 6% 9% 62%	1620
	21st to end	Night	6% 3 2 3 3 2 5% 5% 6% 9% 56%	1620
July	1st to 10th	Night	8% 4 1 5% 5% 3 4 5% 6% 11% 48%	1620
	11th to 20th	Night	3 2 1 3 2 3 3 4 6% 8% 66%	1635
	21st to end	Night	4 2 1 2 2 1 3 4 5% 8% 68%	1969
August	1st to 10th	Night	2 1 2 2 2 2 3 4 8% 74%	1790
	11th to 20th	Night	5% 2 1 3 4 2 4 3 7% 10% 58%	1778
	21st to end	Night	6% 2 1 3 4 2 5% 5% 7% 11% 54%	1980
September	1st to 10th	Night	7% 4 2 4 4 3 3 5% 6% 9% 54%	1890
	11th to 20th	Night	9% 4 2 4 4 3 4 5% 6% 9% 50%	1980
	21st to end	Night	8% 3 1 3 4 2 4 4 7% 9% 55%	1980
October	1st to 10th	Night	7% 2 2 3 3 2 4 3 4 6% 63%	1980
	11th to 20th	Night	12% 3 1 4 4 2 4 4 4 5% 58%	1980
	21st to end	Night	9% 3 1 2 3 1 2 2 3 5% 68%	2266
November	1st to 10th	Night	12% 4 1 3 2 2 2 2 3 5% 63%	2405
	11th to 20th	Night	7% 4 2 3 3 2 3 4 4 6% 63%	2470
	21st to end	Night	11% 4 1 4 4 2 3 4 5% 5% 58%	2470
December	1st to 10th	Night	12% 5% 2 3 3 2 3 4 4 8% 55%	2470
	11th to 20th	Night	11% 6% 2 5% 4 3 3 4 4 6% 53%	3036
	21st to end	Night	11% 5% 1 2 2 2 3 3 5% 8% 57%	4532

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	29% 2 5% 19% 27% 19%	1731
	11th to 20th	Day	31% 3 5% 18% 24% 20%	1840
	21st to end	Day	30% 3 7% 15% 29% 16%	1980
February	1st to 10th	Day	33% 3 6% 14% 24% 21%	1800
	11th to 20th	Day	32% 4 7% 19% 21% 16%	1759
	21st to end	Day	27% 4 7% 14% 26% 22%	1480
March	1st to 10th	Day	36% 4 6% 20% 19% 16%	1800
	11th to 20th	Day	35% 5% 7% 14% 17% 22%	1944
	21st to end	Day	28% 4 10% 17% 19% 22%	2178
April	1st to 10th	Day	30% 4 8% 18% 20% 20%	2150
	11th to 20th	Day	29% 3 9% 20% 19% 20%	2134
	21st to end	Day	31% 3 7% 21% 20% 19%	2160
May	1st to 10th	Day	33% 5% 8% 19% 22% 14%	2218
	11th to 20th	Day	33% 6% 9% 26% 17% 8%	2306
	21st to end	Day	38% 5% 10% 25% 17% 5%	2531
June	1st to 10th	Day	20% 6% 13% 31% 23% 7%	2340
	11th to 20th	Day	23% 6% 12% 26% 25% 8%	2340
	21st to end	Day	27% 7% 14% 26% 19% 7%	2340
July	1st to 10th	Day	34% 8% 16% 26% 14% 2	2276
	11th to 20th	Day	17% 6% 15% 32% 25% 5%	2251
	21st to end	Day	15% 7% 22% 35% 21% 1	2219
August	1st to 10th	Day	14% 5% 13% 41% 23% 4	2136
	11th to 20th	Day	20% 8% 19% 30% 18% 3	2123
	21st to end	Day	27% 8% 16% 26% 18% 5%	2376
September	1st to 10th	Day	35% 8% 11% 22% 17% 6%	2067
	11th to 20th	Day	36% 7% 12% 21% 21% 4	1980
	21st to end	Day	28% 5% 12% 19% 24% 12%	1980
October	1st to 10th	Day	25% 7% 11% 26% 21% 11%	1980
	11th to 20th	Day	33% 4 9% 14% 22% 17%	1980
	21st to end	Day	26% 3 4 15% 30% 21%	2066
November	1st to 10th	Day	30% 3 9% 23% 20% 14%	1673
	11th to 20th	Day	28% 5% 7% 21% 21% 18%	1710
	21st to end	Day	34% 3 6% 17% 23% 16%	1710
December	1st to 10th	Day	34% 4 7% 18% 25% 12%	1710
	11th to 20th	Day	34% 4 7% 16% 21% 17%	2159
	21st to end	Day	30% 2 5% 16% 26% 22%	3135
January	1st to 10th	Night	28% 3 4 16% 26% 23%	2449
	11th to 20th	Night	30% 3 6% 16% 26% 19%	2208
	21st to end	Night	31% 3 6% 15% 24% 22%	2376
February	1st to 10th	Night	27% 4 7% 16% 22% 24%	2160
	11th to 20th	Night	31% 4 7% 17% 22% 19%	2098
	21st to end	Night	28% 4 8% 14% 24% 22%	1776
March	1st to 10th	Night	30% 4 11% 19% 20% 16%	2160
	11th to 20th	Night	32% 5% 8% 15% 18% 23%	2016
	21st to end	Night	26% 4 12% 18% 18% 22%	2178
April	1st to 10th	Night	25% 5% 10% 20% 19% 21%	1805
	11th to 20th	Night	29% 4 8% 19% 17% 22%	1777
	21st to end	Night	27% 3 10% 22% 21% 16%	1800
May	1st to 10th	Night	30% 4 10% 22% 20% 14%	1738
	11th to 20th	Night	32% 5% 11% 24% 20% 7%	1594
	21st to end	Night	32% 6% 14% 24% 19% 5%	1746
June	1st to 10th	Night	16% 7% 15% 34% 24% 5%	1620
	11th to 20th	Night	18% 5% 14% 29% 23% 10%	1620
	21st to end	Night	25% 6% 13% 26% 22% 8%	1620
July	1st to 10th	Night	31% 6% 19% 24% 17% 2	1575
	11th to 20th	Night	16% 7% 11% 30% 28% 8%	1581
	21st to end	Night	13% 6% 20% 35% 24% 2	1859
August	1st to 10th	Night	11% 6% 13% 35% 30% 4	1779
	11th to 20th	Night	20% 7% 17% 32% 19% 4	1778
	21st to end	Night	22% 8% 18% 28% 19% 5%	1980
September	1st to 10th	Night	27% 7% 16% 23% 18% 9%	1890
	11th to 20th	Night	31% 7% 17% 21% 19% 5%	1980
	21st to end	Night	25% 7% 13% 24% 18% 14%	1980
October	1st to 10th	Night	23% 5% 12% 25% 22% 13%	1980
	11th to 20th	Night	28% 4 9% 20% 22% 17%	1980
	21st to end	Night	22% 3 7% 16% 28% 24%	2266
November	1st to 10th	Night	27% 2 8% 21% 26% 16%	2405
	11th to 20th	Night	23% 4 9% 22% 24% 19%	2470
	21st to end	Night	29% 4 7% 20% 21% 19%	2470
December	1st to 10th	Night	29% 4 9% 20% 23% 16%	2470
	11th to 20th	Night	33% 4 6% 16% 21% 20%	3037
	21st to end	Night	26% 4 6% 17% 27% 20%	4532

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	14% 7% 34% 30% 13% 1	270
	11th to 20th	Day	17% 11% 24% 35% 13% 2	252
	21st to end	Day	12% 6% 40% 30% 11% 1	264
February	1st to 10th	Day	15% 9% 27% 33% 14% 3	240
	11th to 20th	Day	21% 8% 32% 28% 10% 2	240
	21st to end	Day	18% 9% 40% 29% 5%	198
March	1st to 10th	Day	18% 7% 40% 28% 6%	240
	11th to 20th	Day	14% 9% 37% 29% 11%	240
	21st to end	Day	12% 13% 35% 33% 6% 1	264
April	1st to 10th	Day	9% 11% 40% 33% 6%	410
	11th to 20th	Day	10% 14% 43% 28% 5%	412
	21st to end	Day	12% 9% 40% 29% 8% 1	420
May	1st to 10th	Day	12% 7% 35% 38% 8%	481
	11th to 20th	Day	17% 5% 32% 34% 10% 1	625
	21st to end	Day	17% 6% 29% 38% 9% 1	679
June	1st to 10th	Day	6% 3 18% 51% 20% 3	630
	11th to 20th	Day	7% 1 21% 48% 19% 3	630
	21st to end	Day	6% 1 13% 46% 27% 7%	630
July	1st to 10th	Day	10% 2 6% 40% 36% 6%	621
	11th to 20th	Day	3 1 4 44% 43% 5%	598
	21st to end	Day	1 4 41% 45% 7%	487
August	1st to 10th	Day	2 4 37% 48% 9%	447
	11th to 20th	Day	6% 3 33% 47% 10%	437
	21st to end	Day	3 1 4 31% 48% 13%	495
September	1st to 10th	Day	8% 1 6% 29% 43% 12%	357
	11th to 20th	Day	7% 1 4 27% 41% 20%	270
	21st to end	Day	12% 1 5% 29% 38% 14%	270
October	1st to 10th	Day	9% 3 13% 37% 36% 2	270
	11th to 20th	Day	17% 3 12% 38% 28% 3	270
	21st to end	Day	16% 6% 22% 31% 21% 3	297
November	1st to 10th	Day	20% 5% 19% 35% 18% 3	270
	11th to 20th	Day	16% 10% 16% 34% 17% 7%	270
	21st to end	Day	19% 10% 30% 27% 11% 3	270
December	1st to 10th	Day	16% 7% 21% 29% 21% 5%	270
	11th to 20th	Day	14% 9% 34% 27% 16% 1	270
	21st to end	Day	19% 6% 25% 30% 20% 1	297
January	1st to 10th	Night	11% 5% 31% 44% 9%	941
	11th to 20th	Night	15% 5% 27% 45% 7%	736
	21st to end	Night	14% 7% 35% 35% 8%	792
February	1st to 10th	Night	13% 6% 36% 37% 8%	720
	11th to 20th	Night	15% 7% 41% 32% 6%	704
	21st to end	Night	11% 7% 48% 33% 1	592
March	1st to 10th	Night	16% 8% 44% 30% 3	720
	11th to 20th	Night	14% 10% 40% 33% 4	576
	21st to end	Night	10% 9% 52% 25% 4	594
April	1st to 10th	Night	7% 7% 54% 29% 3	540
	11th to 20th	Night	14% 8% 50% 26% 1	533
	21st to end	Night	8% 10% 55% 23% 4	540
May	1st to 10th	Night	9% 7% 49% 31% 4	540
	11th to 20th	Night	11% 4 40% 39% 5%	531
	21st to end	Night	11% 5% 42% 35% 6%	584
June	1st to 10th	Night	3 3 31% 57% 7%	540
	11th to 20th	Night	4 1 35% 52% 8%	540
	21st to end	Night	5% 2 25% 50% 17% 1	540
July	1st to 10th	Night	8% 3 11% 57% 19% 2	525
	11th to 20th	Night	4 2 11% 60% 23%	522
	21st to end	Night	3 1 10% 60% 25% 1	591
August	1st to 10th	Night	1 1 6% 62% 28% 2	537
	11th to 20th	Night	6% 1 5% 54% 34% 1	534
	21st to end	Night	5% 1 7% 52% 32% 2	594
September	1st to 10th	Night	7% 2 5% 50% 32% 4	540
	11th to 20th	Night	10% 1 8% 42% 38% 2	540
	21st to end	Night	8% 1 12% 46% 32% 1	540
October	1st to 10th	Night	7% 1 21% 50% 21%	540
	11th to 20th	Night	12% 3 26% 45% 14%	540
	21st to end	Night	10% 6% 25% 41% 16% 2	682
November	1st to 10th	Night	13% 4 22% 44% 17% 1	925
	11th to 20th	Night	9% 4 29% 41% 15% 1	950
	21st to end	Night	13% 4 30% 40% 12%	950
December	1st to 10th	Night	13% 5% 23% 45% 14% 1	950
	11th to 20th	Night	16% 7% 30% 40% 8%	950
	21st to end	Night	13% 5% 34% 40% 8%	1045

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