Panacea
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Panacea clear sky chart from 2005-11-06 to 2025-07-21.

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 6% 4 4 5% 4 7% 9% 45%	120252
	Night	9% 6% 2 6% 4 4 4 4 6% 9% 46%	118850
Transparency	Day	20% 42% 11% 12% 10% 5%	124132
	Night	21% 41% 9% 13% 11% 5%	123107
Seeing	Day	10% 4 18% 28% 26% 13%	15943
	Night	11% 5% 18% 31% 28% 8%	25932

By Month

Percentage Cloud Cover SE (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	11% 4 2 5% 4 3 4 3 4 6% 53%	4056
	11th to 20th	Day	15% 6% 3 6% 4 3 4 3 5% 6% 43%	4152
	21st to end	Day	12% 7% 2 5% 3 3 4 3 6% 9% 45%	4972
February	1st to 10th	Day	15% 7% 2 7% 4 4 4 3 5% 6% 42%	2000
	11th to 20th	Day	16% 8% 2 4 3 3 3 3 4 6% 48%	1948
	21st to end	Day	12% 7% 3 5% 5% 4 4 3 4 7% 46%	1650
March	1st to 10th	Day	18% 7% 2 5% 3 3 3 3 6% 8% 42%	4664
	11th to 20th	Day	6% 5% 2 5% 4 4 5% 4 6% 8% 52%	4980
	21st to end	Day	14% 5% 1 4 3 3 3 3 4 7% 52%	5465
April	1st to 10th	Day	9% 4 2 6% 4 3 4 5% 6% 9% 48%	2200
	11th to 20th	Day	10% 4 2 5% 4 4 4 3 5% 6% 53%	2353
	21st to end	Day	5% 4 1 4 3 3 5% 3 5% 9% 58%	2444
May	1st to 10th	Day	8% 5% 2 6% 4 4 4 4 7% 9% 47%	5862
	11th to 20th	Day	8% 5% 2 5% 3 3 4 3 6% 9% 50%	5861
	21st to end	Day	3 3 1 5% 4 4 5% 5% 7% 12% 52%	6433
June	1st to 10th	Day	7% 5% 2 6% 5% 6% 6% 6% 10% 13% 33%	2600
	11th to 20th	Day	5% 3 2 6% 5% 5% 7% 6% 11% 13% 36%	2600
	21st to end	Day	6% 5% 2 7% 6% 5% 7% 7% 11% 13% 31%	2600
July	1st to 10th	Day	5% 5% 2 7% 5% 6% 7% 7% 11% 15% 29%	4250
	11th to 20th	Day	4 3 1 5% 4 5% 6% 6% 9% 14% 43%	4250
	21st to end	Day	3 4 2 6% 6% 8% 9% 7% 12% 15% 27%	4466
August	1st to 10th	Day	7% 4 2 7% 5% 6% 7% 6% 9% 13% 34%	3817
	11th to 20th	Day	6% 4 1 5% 4 5% 6% 6% 9% 12% 41%	3729
	21st to end	Day	7% 6% 2 7% 6% 6% 7% 6% 9% 13% 33%	4117
September	1st to 10th	Day	9% 7% 3 7% 6% 5% 6% 5% 8% 12% 31%	2090
	11th to 20th	Day	9% 7% 2 7% 6% 6% 6% 5% 8% 10% 34%	2090
	21st to end	Day	10% 5% 2 5% 4 5% 4 4 6% 8% 47%	2090
October	1st to 10th	Day	9% 6% 2 5% 4 4 4 3 5% 8% 48%	2090
	11th to 20th	Day	5% 3 1 3 3 3 3 3 4 7% 65%	2057
	21st to end	Day	7% 4 2 5% 4 4 4 3 5% 5% 57%	2090
November	1st to 10th	Day	7% 4 2 5% 3 4 3 4 5% 7% 57%	1907
	11th to 20th	Day	9% 5% 2 5% 3 3 4 3 5% 6% 54%	1800
	21st to end	Day	9% 5% 2 6% 3 4 4 4 5% 7% 51%	1800
December	1st to 10th	Day	9% 6% 2 6% 4 4 3 3 5% 6% 53%	2930
	11th to 20th	Day	11% 7% 2 5% 4 3 4 3 5% 6% 51%	3373
	21st to end	Day	16% 9% 3 6% 4 4 3 3 4 5% 43%	4466
January	1st to 10th	Night	11% 6% 2 4 3 3 3 3 4 7% 53%	5889
	11th to 20th	Night	15% 7% 3 8% 5% 4 5% 4 6% 8% 36%	5790
	21st to end	Night	15% 8% 3 6% 3 4 3 3 6% 9% 41%	5984
February	1st to 10th	Night	15% 8% 2 6% 4 4 4 4 5% 8% 43%	2400
	11th to 20th	Night	14% 8% 3 6% 4 4 3 3 4 5% 46%	2338
	21st to end	Night	13% 9% 3 7% 3 4 3 3 4 5% 46%	1980
March	1st to 10th	Night	14% 9% 3 7% 4 4 4 3 5% 7% 40%	5175
	11th to 20th	Night	7% 5% 1 5% 3 3 4 3 6% 9% 53%	4980
	21st to end	Night	14% 5% 2 5% 4 3 3 3 4 7% 49%	5467
April	1st to 10th	Night	9% 5% 2 5% 4 4 4 4 6% 8% 48%	2200
	11th to 20th	Night	8% 5% 2 6% 4 4 4 3 6% 7% 51%	2010
	21st to end	Night	4 4 2 4 4 4 4 4 6% 8% 57%	1955
May	1st to 10th	Night	6% 4 2 4 3 3 4 4 7% 11% 53%	4033
	11th to 20th	Night	9% 5% 2 5% 3 4 4 4 6% 9% 49%	4032
	21st to end	Night	3 2 1 4 3 4 4 4 6% 11% 59%	4421
June	1st to 10th	Night	7% 5% 2 6% 3 5% 6% 5% 8% 13% 40%	1800
	11th to 20th	Night	4 5% 2 6% 6% 5% 4 4 10% 13% 43%	1800
	21st to end	Night	5% 5% 2 6% 4 5% 5% 6% 10% 12% 42%	1800
July	1st to 10th	Night	4 4 2 8% 6% 7% 9% 8% 11% 16% 26%	2930
	11th to 20th	Night	3 3 1 4 4 4 5% 5% 8% 14% 48%	2930
	21st to end	Night	3 3 2 5% 6% 6% 7% 6% 11% 16% 35%	3087
August	1st to 10th	Night	6% 4 1 5% 5% 5% 6% 6% 10% 14% 39%	3106
	11th to 20th	Night	4 3 1 5% 5% 5% 6% 6% 9% 14% 43%	3100
	21st to end	Night	7% 5% 3 8% 6% 7% 8% 7% 9% 13% 27%	3504
September	1st to 10th	Night	8% 7% 2 9% 7% 6% 6% 6% 9% 11% 29%	2090
	11th to 20th	Night	10% 6% 3 7% 6% 7% 7% 5% 7% 10% 32%	2090
	21st to end	Night	8% 5% 2 6% 4 4 5% 4 8% 9% 44%	2090
October	1st to 10th	Night	8% 7% 2 7% 4 5% 3 4 5% 8% 47%	2090
	11th to 20th	Night	5% 4 2 4 3 3 4 3 5% 7% 60%	2123
	21st to end	Night	7% 4 3 5% 4 3 4 4 6% 7% 53%	2508
November	1st to 10th	Night	6% 5% 2 6% 4 5% 5% 4 6% 7% 52%	2386
	11th to 20th	Night	10% 6% 2 5% 4 3 4 4 5% 6% 52%	2600
	21st to end	Night	10% 6% 2 5% 4 3 3 4 5% 6% 51%	2600
December	1st to 10th	Night	9% 5% 1 5% 4 4 4 3 5% 7% 53%	4250
	11th to 20th	Night	10% 6% 2 5% 4 3 3 3 4 6% 54%	4822
	21st to end	Night	13% 8% 3 7% 4 4 4 3 5% 5% 44%	6490

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% 28% 4 11% 24% 9%	4057
	11th to 20th	Day	33% 28% 3 9% 16% 10%	4152
	21st to end	Day	24% 30% 8% 15% 15% 8%	4972
February	1st to 10th	Day	15% 63% 5% 6% 6% 4	2000
	11th to 20th	Day	16% 61% 2 9% 9% 3	1958
	21st to end	Day	15% 62% 4 5% 8% 6%	1650
March	1st to 10th	Day	32% 31% 9% 10% 12% 6%	4664
	11th to 20th	Day	20% 32% 8% 11% 15% 14%	4980
	21st to end	Day	24% 30% 8% 19% 10% 8%	5465
April	1st to 10th	Day	13% 63% 6% 7% 6% 5%	2200
	11th to 20th	Day	13% 62% 3 9% 8% 5%	2353
	21st to end	Day	10% 62% 5% 11% 8% 3	2444
May	1st to 10th	Day	26% 33% 14% 17% 8% 3	5897
	11th to 20th	Day	22% 30% 12% 25% 9% 1	5865
	21st to end	Day	15% 32% 17% 22% 12% 2	6447
June	1st to 10th	Day	15% 65% 10% 7% 3	2600
	11th to 20th	Day	15% 66% 10% 5% 3	2600
	21st to end	Day	14% 64% 12% 7% 3	2600
July	1st to 10th	Day	23% 44% 29% 4	4185
	11th to 20th	Day	14% 41% 37% 7%	4181
	21st to end	Day	25% 50% 20% 5%	4324
August	1st to 10th	Day	22% 41% 17% 12% 6% 1	3804
	11th to 20th	Day	13% 42% 18% 19% 8%	3765
	21st to end	Day	20% 42% 21% 13% 3	4117
September	1st to 10th	Day	17% 64% 9% 4 4 1	2090
	11th to 20th	Day	14% 63% 9% 8% 5% 1	2090
	21st to end	Day	13% 61% 7% 12% 5% 2	2090
October	1st to 10th	Day	31% 38% 5% 7% 11% 9%	3480
	11th to 20th	Day	4 36% 2 12% 23% 22%	3401
	21st to end	Day	6% 37% 3 15% 31% 8%	3428
November	1st to 10th	Day	15% 57% 6% 9% 8% 6%	1907
	11th to 20th	Day	16% 57% 4 6% 12% 5%	1800
	21st to end	Day	15% 57% 4 9% 11% 5%	1800
December	1st to 10th	Day	20% 36% 6% 10% 19% 9%	2930
	11th to 20th	Day	20% 33% 5% 15% 19% 8%	3370
	21st to end	Day	34% 28% 6% 13% 18% 2	4466
January	1st to 10th	Night	23% 26% 5% 10% 23% 13%	5889
	11th to 20th	Night	38% 27% 3 11% 15% 5%	5790
	21st to end	Night	28% 29% 7% 16% 14% 6%	5984
February	1st to 10th	Night	16% 63% 3 7% 9% 3	2400
	11th to 20th	Night	17% 61% 3 7% 8% 4	2339
	21st to end	Night	16% 62% 4 6% 7% 5%	1980
March	1st to 10th	Night	35% 31% 7% 10% 12% 6%	5175
	11th to 20th	Night	20% 30% 7% 14% 14% 15%	4980
	21st to end	Night	28% 30% 4 17% 12% 9%	5467
April	1st to 10th	Night	15% 63% 3 7% 6% 6%	2200
	11th to 20th	Night	12% 62% 2 8% 9% 7%	2010
	21st to end	Night	10% 62% 5% 13% 7% 4	1955
May	1st to 10th	Night	18% 33% 18% 22% 7% 3	4060
	11th to 20th	Night	24% 31% 11% 23% 11% 1	4033
	21st to end	Night	12% 31% 15% 30% 11% 1	4429
June	1st to 10th	Night	14% 64% 10% 8% 3	1800
	11th to 20th	Night	12% 66% 13% 7% 3	1800
	21st to end	Night	11% 64% 12% 10% 4	1800
July	1st to 10th	Night	28% 44% 22% 6%	2885
	11th to 20th	Night	12% 41% 35% 11% 1	2876
	21st to end	Night	23% 45% 25% 6% 1	2988
August	1st to 10th	Night	20% 41% 19% 13% 7%	3095
	11th to 20th	Night	13% 42% 19% 21% 5%	3130
	21st to end	Night	25% 44% 18% 10% 3	3504
September	1st to 10th	Night	19% 63% 7% 5% 4 1	2090
	11th to 20th	Night	14% 63% 10% 8% 4 1	2090
	21st to end	Night	12% 61% 8% 10% 7% 1	2090
October	1st to 10th	Night	32% 38% 5% 8% 10% 6%	3480
	11th to 20th	Night	6% 37% 2 13% 22% 20%	3518
	21st to end	Night	7% 37% 3 14% 30% 9%	4120
November	1st to 10th	Night	18% 56% 5% 9% 7% 4	2386
	11th to 20th	Night	18% 57% 3 8% 10% 5%	2600
	21st to end	Night	15% 57% 4 8% 10% 5%	2600
December	1st to 10th	Night	21% 36% 5% 10% 15% 13%	4250
	11th to 20th	Night	20% 33% 7% 15% 16% 9%	4824
	21st to end	Night	32% 28% 6% 14% 16% 3	6490

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	12% 8% 42% 30% 7% 1	300
	11th to 20th	Day	9% 10% 33% 35% 10% 3	300
	21st to end	Day	22% 7% 39% 27% 5%	330
February	1st to 10th	Day	17% 9% 31% 26% 16% 1	300
	11th to 20th	Day	23% 8% 30% 30% 9%	300
	21st to end	Day	12% 6% 40% 31% 9% 1	249
March	1st to 10th	Day	12% 9% 38% 31% 11% 1	380
	11th to 20th	Day	11% 9% 33% 32% 12% 1	500
	21st to end	Day	14% 8% 31% 32% 14% 2	550
April	1st to 10th	Day	11% 8% 31% 34% 15% 2	500
	11th to 20th	Day	10% 6% 29% 33% 19% 3	492
	21st to end	Day	6% 3 24% 37% 25% 5%	500
May	1st to 10th	Day	5% 5% 22% 40% 21% 6%	503
	11th to 20th	Day	9% 5% 14% 34% 27% 12%	527
	21st to end	Day	8% 2 9% 32% 33% 16%	573
June	1st to 10th	Day	9% 2 8% 31% 35% 15%	530
	11th to 20th	Day	6% 2 7% 23% 38% 24%	530
	21st to end	Day	6% 1 3 23% 40% 26%	530
July	1st to 10th	Day	7% 2 4 14% 35% 38%	525
	11th to 20th	Day	5% 2 2 15% 37% 39%	524
	21st to end	Day	5% 2 3 17% 39% 34%	532
August	1st to 10th	Day	10% 2 3 16% 40% 29%	486
	11th to 20th	Day	8% 1 4 13% 37% 37%	479
	21st to end	Day	8% 2 7% 20% 38% 25%	539
September	1st to 10th	Day	10% 4 6% 18% 35% 27%	490
	11th to 20th	Day	12% 3 8% 23% 36% 18%	490
	21st to end	Day	12% 1 6% 23% 39% 19%	490
October	1st to 10th	Day	12% 3 16% 33% 28% 7%	490
	11th to 20th	Day	5% 2 14% 31% 37% 10%	490
	21st to end	Day	7% 4 17% 36% 32% 4	539
November	1st to 10th	Day	9% 5% 18% 36% 27% 7%	445
	11th to 20th	Day	12% 5% 24% 40% 15% 4	300
	21st to end	Day	10% 5% 28% 35% 19% 2	300
December	1st to 10th	Day	15% 7% 31% 28% 14% 5%	300
	11th to 20th	Day	16% 7% 29% 34% 13% 2	300
	21st to end	Day	20% 4 24% 32% 17% 3	330
January	1st to 10th	Night	17% 9% 35% 29% 9% 1	800
	11th to 20th	Night	14% 8% 29% 33% 15% 2	800
	21st to end	Night	19% 8% 32% 31% 10%	880
February	1st to 10th	Night	16% 8% 25% 35% 14% 1	800
	11th to 20th	Night	19% 9% 26% 33% 12% 1	783
	21st to end	Night	16% 7% 29% 37% 10%	660
March	1st to 10th	Night	14% 7% 27% 36% 15% 1	800
	11th to 20th	Night	12% 5% 26% 36% 21% 1	800
	21st to end	Night	12% 7% 24% 38% 19% 1	880
April	1st to 10th	Night	10% 6% 26% 36% 21% 1	800
	11th to 20th	Night	9% 6% 25% 35% 24% 2	628
	21st to end	Night	6% 4 20% 37% 31% 3	600
May	1st to 10th	Night	7% 2 18% 37% 31% 6%	600
	11th to 20th	Night	7% 2 15% 37% 34% 6%	591
	21st to end	Night	5% 2 6% 34% 44% 10%	650
June	1st to 10th	Night	9% 1 5% 30% 47% 9%	600
	11th to 20th	Night	5% 2 5% 26% 42% 22%	600
	21st to end	Night	6% 2 4 20% 46% 22%	600
July	1st to 10th	Night	6% 2 4 13% 45% 30%	585
	11th to 20th	Night	6% 2 2 9% 45% 37%	582
	21st to end	Night	3 1 1 11% 52% 31%	624
August	1st to 10th	Night	8% 1 2 13% 49% 28%	567
	11th to 20th	Night	5% 1 3 13% 48% 30%	564
	21st to end	Night	9% 3 5% 20% 40% 23%	642
September	1st to 10th	Night	9% 2 6% 22% 42% 18%	760
	11th to 20th	Night	11% 2 8% 28% 39% 12%	760
	21st to end	Night	10% 2 11% 28% 39% 10%	760
October	1st to 10th	Night	10% 2 18% 33% 31% 5%	760
	11th to 20th	Night	6% 3 18% 37% 30% 6%	760
	21st to end	Night	8% 4 17% 40% 27% 3	836
November	1st to 10th	Night	9% 4 23% 38% 24% 2	780
	11th to 20th	Night	12% 8% 24% 36% 19% 2	800
	21st to end	Night	12% 5% 26% 37% 18% 2	800
December	1st to 10th	Night	16% 6% 24% 32% 18% 3	800
	11th to 20th	Night	14% 7% 26% 34% 19% 1	800
	21st to end	Night	19% 6% 25% 32% 16% 1	880

Page generated at 2025-07-18 01:10:01. Version ac07

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