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 2024-11-30.

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 5% 7% 58%	105152
	Night	9% 4 1 4 3 3 3 3 5% 7% 60%	103086
Transparency	Day	27% 5% 10% 22% 22% 14%	104928
	Night	25% 4 10% 22% 23% 16%	102900
Seeing	Day	11% 5% 22% 35% 23% 4	14783
	Night	10% 5% 30% 42% 13% 1	24804

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% 8% 1 4 2 2 2 2 3 5% 65%	2883
	11th to 20th	Day	7% 6% 2 3 2 2 2 2 4 6% 64%	3170
	21st to end	Day	9% 7% 2 5% 3 3 3 3 4 7% 53%	3487
February	1st to 10th	Day	9% 8% 2 5% 4 4 3 2 4 4 56%	1900
	11th to 20th	Day	11% 7% 2 4 2 3 2 2 4 5% 55%	1849
	21st to end	Day	10% 5% 2 3 3 2 2 4 4 8% 57%	1570
March	1st to 10th	Day	12% 7% 2 4 3 3 3 3 4 6% 53%	3130
	11th to 20th	Day	20% 8% 2 6% 4 3 3 3 4 5% 44%	3418
	21st to end	Day	8% 5% 2 5% 4 3 3 4 6% 6% 55%	3814
April	1st to 10th	Day	9% 4 2 5% 3 3 4 3 5% 7% 55%	2270
	11th to 20th	Day	13% 4 2 4 3 2 3 2 5% 6% 56%	2251
	21st to end	Day	13% 5% 2 4 3 3 2 3 4 6% 55%	2280
May	1st to 10th	Day	18% 5% 2 5% 3 3 3 3 4 6% 50%	3914
	11th to 20th	Day	14% 5% 1 4 3 3 3 3 4 7% 54%	4082
	21st to end	Day	11% 5% 1 4 3 3 3 3 6% 7% 52%	4489
June	1st to 10th	Day	6% 3 1 3 3 2 3 4 6% 9% 60%	2470
	11th to 20th	Day	8% 4 1 3 3 3 4 4 5% 7% 59%	2470
	21st to end	Day	7% 4 1 4 4 4 4 4 7% 10% 52%	2470
July	1st to 10th	Day	7% 3 1 4 3 4 3 4 5% 7% 58%	4120
	11th to 20th	Day	4 3 1 3 3 3 4 4 6% 8% 61%	4072
	21st to end	Day	6% 3 1 4 3 3 4 3 6% 9% 58%	4118
August	1st to 10th	Day	1 1 2 2 2 3 2 4 7% 76%	3784
	11th to 20th	Day	3 1 1 2 2 2 3 3 4 8% 70%	3726
	21st to end	Day	5% 2 1 4 4 4 4 5% 6% 9% 56%	4180
September	1st to 10th	Day	10% 4 2 5% 5% 5% 5% 5% 5% 8% 45%	2181
	11th to 20th	Day	11% 6% 2 5% 4 4 4 4 5% 8% 46%	2090
	21st to end	Day	9% 4 2 5% 3 4 3 3 5% 7% 56%	2090
October	1st to 10th	Day	4 2 1 2 2 2 3 2 4 5% 72%	3480
	11th to 20th	Day	14% 5% 3 5% 3 3 2 2 2 4 58%	3458
	21st to end	Day	11% 4 1 3 2 2 2 1 3 4 68%	3571
November	1st to 10th	Day	14% 5% 1 3 2 3 2 3 4 6% 56%	1763
	11th to 20th	Day	9% 5% 2 4 3 3 3 3 4 5% 60%	1800
	21st to end	Day	12% 8% 2 4 3 3 3 2 4 5% 53%	1796
December	1st to 10th	Day	15% 7% 2 4 3 2 3 3 4 5% 52%	1710
	11th to 20th	Day	12% 7% 2 5% 3 3 4 3 5% 6% 50%	2161
	21st to end	Day	13% 6% 2 4 2 2 2 2 3 5% 59%	3135
January	1st to 10th	Night	8% 5% 2 3 3 2 3 2 4 7% 62%	4099
	11th to 20th	Night	7% 5% 1 2 2 2 2 2 3 5% 69%	3800
	21st to end	Night	12% 6% 2 5% 3 2 2 3 4 7% 54%	4180
February	1st to 10th	Night	8% 6% 2 4 3 3 3 3 5% 5% 59%	2280
	11th to 20th	Night	12% 6% 2 4 3 2 3 3 5% 6% 55%	2218
	21st to end	Night	9% 5% 1 4 3 4 3 3 5% 6% 57%	1884
March	1st to 10th	Night	7% 5% 1 4 3 3 4 3 5% 7% 58%	3734
	11th to 20th	Night	17% 7% 2 5% 3 2 2 3 4 5% 48%	3530
	21st to end	Night	8% 5% 2 4 3 4 4 3 4 5% 58%	3817
April	1st to 10th	Night	7% 4 2 4 3 2 3 3 6% 7% 59%	1905
	11th to 20th	Night	13% 4 1 4 3 3 3 3 4 5% 56%	1877
	21st to end	Night	11% 5% 1 4 3 3 2 2 3 6% 60%	1900
May	1st to 10th	Night	16% 6% 1 4 3 3 3 3 3 5% 52%	3052
	11th to 20th	Night	10% 4 1 5% 3 3 4 3 4 6% 56%	2823
	21st to end	Night	9% 3 1 4 4 3 4 3 6% 8% 55%	3098
June	1st to 10th	Night	3 2 1 3 3 3 4 3 6% 11% 62%	1710
	11th to 20th	Night	4 2 1 3 3 3 4 4 6% 9% 62%	1710
	21st to end	Night	6% 4 1 3 3 4 4 4 6% 8% 57%	1710
July	1st to 10th	Night	5% 3 1 4 3 3 4 3 6% 9% 59%	2850
	11th to 20th	Night	3 2 1 3 2 3 4 3 6% 9% 63%	2879
	21st to end	Night	7% 3 1 3 2 2 4 3 5% 8% 61%	3445
August	1st to 10th	Night	1 1 1 2 1 2 2 3 4 7% 76%	3155
	11th to 20th	Night	3 2 1 2 3 3 4 2 7% 9% 66%	3113
	21st to end	Night	6% 3 1 4 3 3 4 3 6% 11% 55%	3487
September	1st to 10th	Night	7% 4 2 5% 4 4 4 3 6% 9% 53%	1996
	11th to 20th	Night	9% 4 2 5% 4 3 4 4 6% 8% 50%	2090
	21st to end	Night	8% 3 1 4 3 3 4 3 7% 8% 56%	2090
October	1st to 10th	Night	4 2 1 3 2 2 2 2 3 4 73%	3480
	11th to 20th	Night	12% 3 1 4 2 2 3 2 3 3 63%	3460
	21st to end	Night	7% 2 1 2 2 2 2 2 2 4 75%	3941
November	1st to 10th	Night	12% 4 1 4 2 3 2 2 3 5% 62%	2535
	11th to 20th	Night	7% 4 1 3 2 3 3 3 4 6% 63%	2600
	21st to end	Night	10% 4 1 4 3 3 3 3 5% 5% 59%	2600
December	1st to 10th	Night	12% 6% 2 3 2 2 3 3 4 8% 55%	2470
	11th to 20th	Night	11% 6% 2 5% 3 4 3 3 4 5% 53%	3036
	21st to end	Night	11% 5% 1 3 2 2 3 2 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	24% 2 4 14% 26% 30%	2884
	11th to 20th	Day	23% 2 6% 19% 27% 22%	3170
	21st to end	Day	32% 4 6% 19% 29% 10%	3487
February	1st to 10th	Day	33% 3 6% 14% 24% 21%	1900
	11th to 20th	Day	31% 4 7% 20% 21% 17%	1859
	21st to end	Day	27% 4 7% 15% 27% 21%	1570
March	1st to 10th	Day	34% 3 6% 16% 20% 20%	3130
	11th to 20th	Day	43% 5% 7% 11% 17% 16%	3418
	21st to end	Day	28% 6% 9% 15% 17% 26%	3814
April	1st to 10th	Day	29% 4 8% 18% 20% 22%	2270
	11th to 20th	Day	30% 3 9% 19% 18% 20%	2254
	21st to end	Day	31% 3 7% 21% 19% 19%	2280
May	1st to 10th	Day	35% 6% 7% 14% 19% 19%	3914
	11th to 20th	Day	31% 5% 7% 23% 18% 15%	4086
	21st to end	Day	29% 7% 10% 26% 17% 11%	4489
June	1st to 10th	Day	21% 6% 13% 31% 23% 7%	2470
	11th to 20th	Day	24% 6% 11% 25% 26% 8%	2470
	21st to end	Day	27% 7% 14% 26% 20% 7%	2470
July	1st to 10th	Day	24% 6% 17% 34% 18% 1	4056
	11th to 20th	Day	19% 6% 19% 35% 19% 3	4003
	21st to end	Day	21% 6% 17% 28% 26% 3	3988
August	1st to 10th	Day	10% 4 10% 38% 35% 4	3772
	11th to 20th	Day	13% 5% 19% 43% 17% 2	3762
	21st to end	Day	23% 8% 17% 26% 23% 4	4179
September	1st to 10th	Day	36% 8% 11% 22% 16% 8%	2181
	11th to 20th	Day	35% 7% 11% 21% 21% 5%	2090
	21st to end	Day	27% 5% 12% 19% 23% 13%	2090
October	1st to 10th	Day	15% 5% 7% 15% 21% 37%	3480
	11th to 20th	Day	33% 3 6% 12% 17% 29%	3458
	21st to end	Day	24% 2 4 16% 40% 14%	3571
November	1st to 10th	Day	30% 4 9% 22% 20% 15%	1763
	11th to 20th	Day	27% 5% 7% 21% 21% 19%	1800
	21st to end	Day	34% 3 6% 17% 23% 16%	1796
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	23% 3 4 12% 31% 27%	4099
	11th to 20th	Night	21% 2 4 18% 27% 28%	3800
	21st to end	Night	31% 4 5% 17% 27% 15%	4180
February	1st to 10th	Night	27% 4 7% 17% 22% 24%	2280
	11th to 20th	Night	31% 4 7% 17% 23% 19%	2218
	21st to end	Night	28% 4 8% 14% 25% 22%	1884
March	1st to 10th	Night	24% 4 10% 19% 25% 18%	3734
	11th to 20th	Night	39% 5% 8% 14% 19% 16%	3530
	21st to end	Night	27% 5% 11% 17% 15% 25%	3817
April	1st to 10th	Night	25% 5% 10% 20% 19% 22%	1905
	11th to 20th	Night	30% 4 8% 19% 17% 21%	1877
	21st to end	Night	28% 3 10% 22% 21% 16%	1900
May	1st to 10th	Night	34% 4 9% 19% 18% 16%	3052
	11th to 20th	Night	29% 5% 9% 21% 22% 14%	2824
	21st to end	Night	26% 7% 12% 27% 16% 12%	3099
June	1st to 10th	Night	16% 7% 15% 34% 24% 5%	1710
	11th to 20th	Night	18% 5% 14% 28% 24% 10%	1710
	21st to end	Night	24% 6% 12% 27% 23% 8%	1710
July	1st to 10th	Night	22% 5% 18% 36% 17% 1	2805
	11th to 20th	Night	18% 7% 16% 34% 21% 5%	2825
	21st to end	Night	21% 6% 16% 30% 26% 1	3336
August	1st to 10th	Night	10% 5% 10% 37% 35% 3	3144
	11th to 20th	Night	15% 6% 18% 44% 15% 3	3143
	21st to end	Night	24% 7% 17% 26% 23% 3	3487
September	1st to 10th	Night	28% 7% 15% 22% 18% 10%	1996
	11th to 20th	Night	30% 7% 16% 21% 19% 6%	2090
	21st to end	Night	24% 6% 12% 24% 17% 16%	2090
October	1st to 10th	Night	16% 4 7% 15% 20% 38%	3480
	11th to 20th	Night	28% 3 6% 13% 20% 30%	3460
	21st to end	Night	17% 2 5% 18% 41% 16%	3941
November	1st to 10th	Night	28% 2 8% 20% 26% 17%	2535
	11th to 20th	Night	23% 4 9% 22% 23% 20%	2600
	21st to end	Night	28% 3 7% 21% 21% 19%	2600
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	16% 10% 26% 35% 12% 1	270
	21st to end	Day	12% 6% 38% 29% 14% 1	297
February	1st to 10th	Day	17% 9% 27% 32% 13% 2	270
	11th to 20th	Day	19% 9% 33% 28% 10% 1	270
	21st to end	Day	16% 8% 40% 30% 5%	225
March	1st to 10th	Day	17% 8% 39% 29% 6%	270
	11th to 20th	Day	15% 10% 36% 28% 11%	270
	21st to end	Day	11% 14% 38% 31% 6% 1	297
April	1st to 10th	Day	9% 12% 40% 32% 6% 1	450
	11th to 20th	Day	10% 13% 44% 28% 5%	452
	21st to end	Day	12% 10% 41% 29% 8% 1	460
May	1st to 10th	Day	12% 8% 35% 37% 8%	525
	11th to 20th	Day	16% 6% 33% 33% 10% 1	675
	21st to end	Day	16% 6% 30% 38% 8% 1	734
June	1st to 10th	Day	6% 3 19% 49% 20% 3	680
	11th to 20th	Day	8% 1 22% 48% 18% 3	680
	21st to end	Day	6% 1 13% 46% 27% 6%	680
July	1st to 10th	Day	9% 2 6% 41% 36% 6%	671
	11th to 20th	Day	3 1 5% 43% 41% 6%	646
	21st to end	Day	1 5% 42% 44% 8%	531
August	1st to 10th	Day	1 4 37% 48% 9%	487
	11th to 20th	Day	5% 4 35% 45% 9%	477
	21st to end	Day	3 1 5% 32% 47% 13%	539
September	1st to 10th	Day	8% 1 7% 29% 42% 13%	391
	11th to 20th	Day	7% 1 5% 30% 38% 18%	300
	21st to end	Day	12% 2 5% 29% 37% 15%	300
October	1st to 10th	Day	8% 2 12% 35% 38% 5%	300
	11th to 20th	Day	16% 3 12% 38% 26% 4	300
	21st to end	Day	16% 6% 22% 33% 20% 4	330
November	1st to 10th	Day	20% 5% 22% 33% 18% 2	300
	11th to 20th	Day	16% 9% 18% 32% 17% 7%	300
	21st to end	Day	17% 10% 28% 29% 13% 3	299
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	14% 5% 28% 45% 7%	760
	21st to end	Night	14% 8% 35% 36% 8%	836
February	1st to 10th	Night	13% 6% 37% 36% 8%	760
	11th to 20th	Night	15% 8% 41% 31% 6%	744
	21st to end	Night	11% 7% 47% 33% 1	628
March	1st to 10th	Night	15% 9% 44% 30% 3	760
	11th to 20th	Night	14% 10% 40% 32% 4	607
	21st to end	Night	10% 10% 52% 24% 4	627
April	1st to 10th	Night	7% 9% 53% 28% 2	570
	11th to 20th	Night	14% 9% 50% 26% 1	563
	21st to end	Night	8% 11% 54% 22% 4	570
May	1st to 10th	Night	9% 7% 49% 30% 4	570
	11th to 20th	Night	11% 5% 41% 38% 5%	561
	21st to end	Night	11% 6% 43% 34% 6%	617
June	1st to 10th	Night	2 3 32% 55% 7%	570
	11th to 20th	Night	4 1 36% 51% 8%	570
	21st to end	Night	5% 2 25% 50% 17% 1	570
July	1st to 10th	Night	8% 3 11% 57% 19% 2	555
	11th to 20th	Night	4 2 12% 59% 23%	552
	21st to end	Night	3 1 11% 59% 25% 1	624
August	1st to 10th	Night	2 1 7% 61% 28% 2	567
	11th to 20th	Night	5% 1 5% 55% 32% 1	564
	21st to end	Night	5% 1 8% 52% 31% 2	627
September	1st to 10th	Night	7% 2 5% 49% 33% 4	570
	11th to 20th	Night	10% 1 8% 43% 36% 2	570
	21st to end	Night	8% 1 12% 46% 32% 1	570
October	1st to 10th	Night	7% 1 20% 50% 22%	570
	11th to 20th	Night	12% 3 25% 47% 13%	570
	21st to end	Night	10% 6% 25% 43% 15% 2	721
November	1st to 10th	Night	13% 4 22% 43% 17% 1	975
	11th to 20th	Night	9% 4 30% 41% 15% 1	1000
	21st to end	Night	12% 4 31% 41% 12%	1000
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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