Pane Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pane Observing Site clear sky chart from 2005-11-06 to 2025-06-10.

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	17% 10% 4 9% 5% 5% 4 4 5% 7% 30%	119499
	Night	18% 11% 4 9% 5% 4 4 3 5% 6% 31%	118696
Transparency	Day	51% 6% 11% 20% 10% 1	123145
	Night	52% 6% 11% 19% 11% 2	123187
Seeing	Day	22% 15% 28% 21% 11% 4	15405
	Night	22% 12% 27% 27% 12% 1	25173

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	16% 19% 8% 21% 5% 3 3 2 3 5% 15%	4038
	11th to 20th	Day	13% 22% 10% 17% 8% 7% 2 2 2 2 15%	4060
	21st to end	Day	21% 19% 6% 13% 8% 5% 3 2 4 4 15%	4466
February	1st to 10th	Day	21% 17% 6% 11% 7% 4 3 2 4 5% 21%	1800
	11th to 20th	Day	17% 14% 7% 13% 6% 5% 4 3 5% 5% 21%	1753
	21st to end	Day	20% 15% 5% 10% 6% 3 4 3 4 6% 25%	1651
March	1st to 10th	Day	18% 12% 6% 9% 5% 4 3 3 4 6% 30%	4935
	11th to 20th	Day	13% 9% 4 8% 5% 5% 5% 3 5% 6% 37%	4980
	21st to end	Day	20% 10% 3 8% 5% 4 4 3 5% 6% 30%	5465
April	1st to 10th	Day	16% 13% 4 8% 4 5% 4 4 5% 7% 29%	2304
	11th to 20th	Day	17% 11% 3 8% 5% 4 5% 4 5% 6% 33%	2417
	21st to end	Day	21% 9% 3 7% 4 4 4 4 4 7% 33%	2600
May	1st to 10th	Day	23% 8% 3 8% 5% 5% 5% 4 6% 6% 27%	5862
	11th to 20th	Day	19% 8% 3 8% 5% 5% 5% 4 6% 8% 30%	5861
	21st to end	Day	19% 7% 2 6% 4 4 5% 4 6% 8% 33%	6798
June	1st to 10th	Day	15% 7% 3 6% 5% 5% 5% 5% 7% 8% 34%	2786
	11th to 20th	Day	14% 7% 3 7% 5% 5% 5% 4 6% 9% 36%	2660
	21st to end	Day	13% 7% 2 7% 5% 5% 4 4 6% 9% 38%	2660
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 4 6% 8% 41%	4313
	11th to 20th	Day	11% 6% 2 6% 5% 5% 4 4 6% 10% 41%	4120
	21st to end	Day	12% 6% 2 7% 6% 6% 5% 5% 6% 7% 37%	4466
August	1st to 10th	Day	15% 6% 3 8% 6% 6% 6% 5% 7% 8% 31%	4104
	11th to 20th	Day	13% 6% 2 7% 6% 5% 6% 5% 7% 9% 36%	4044
	21st to end	Day	9% 4 2 7% 5% 6% 6% 5% 6% 9% 41%	4321
September	1st to 10th	Day	15% 7% 2 5% 3 3 5% 3 5% 8% 44%	2280
	11th to 20th	Day	11% 6% 2 5% 4 5% 5% 3 5% 9% 44%	2091
	21st to end	Day	19% 8% 2 8% 5% 4 4 3 4 6% 36%	2090
October	1st to 10th	Day	15% 6% 2 6% 4 4 5% 4 7% 8% 40%	1900
	11th to 20th	Day	19% 8% 2 8% 5% 5% 5% 3 5% 5% 34%	1900
	21st to end	Day	23% 10% 2 6% 4 4 4 3 5% 7% 32%	2090
November	1st to 10th	Day	12% 8% 3 7% 5% 4 5% 4 4 6% 42%	1867
	11th to 20th	Day	17% 14% 3 7% 5% 4 4 3 6% 5% 32%	1667
	21st to end	Day	17% 16% 5% 10% 5% 4 4 4 4 5% 24%	1600
December	1st to 10th	Day	20% 14% 7% 16% 5% 3 3 3 4 4 20%	2600
	11th to 20th	Day	25% 18% 6% 11% 4 3 3 3 3 5% 22%	2990
	21st to end	Day	24% 21% 6% 11% 5% 4 4 3 4 5% 13%	3960
January	1st to 10th	Night	15% 18% 8% 23% 5% 4 4 3 3 3 15%	5889
	11th to 20th	Night	15% 18% 9% 16% 9% 6% 4 3 3 4 15%	5900
	21st to end	Night	23% 16% 7% 12% 6% 4 4 2 3 3 20%	6490
February	1st to 10th	Night	22% 14% 4 10% 6% 4 4 3 4 5% 24%	2600
	11th to 20th	Night	20% 13% 4 12% 5% 5% 4 4 4 5% 24%	2533
	21st to end	Night	20% 13% 4 11% 5% 4 5% 3 4 5% 24%	1974
March	1st to 10th	Night	23% 11% 4 9% 4 3 3 2 4 5% 32%	4918
	11th to 20th	Night	14% 10% 4 7% 3 4 4 3 5% 7% 40%	4980
	21st to end	Night	19% 11% 3 8% 5% 4 3 3 4 4 35%	5467
April	1st to 10th	Night	19% 12% 3 7% 5% 4 4 3 4 6% 33%	2095
	11th to 20th	Night	17% 8% 3 7% 5% 5% 4 4 5% 6% 36%	1949
	21st to end	Night	15% 9% 3 6% 5% 3 4 4 6% 8% 37%	1800
May	1st to 10th	Night	27% 11% 3 7% 4 4 4 3 5% 7% 25%	4033
	11th to 20th	Night	18% 9% 3 7% 5% 4 3 3 5% 8% 36%	4032
	21st to end	Night	20% 7% 2 6% 4 3 5% 4 6% 8% 36%	4038
June	1st to 10th	Night	10% 6% 3 6% 5% 4 4 4 6% 8% 43%	1598
	11th to 20th	Night	11% 5% 3 6% 4 5% 4 4 7% 9% 41%	1520
	21st to end	Night	10% 4 2 6% 5% 6% 5% 5% 6% 8% 44%	1520
July	1st to 10th	Night	12% 7% 2 7% 4 5% 4 4 6% 7% 42%	2642
	11th to 20th	Night	12% 4 2 6% 5% 4 4 4 6% 9% 44%	2840
	21st to end	Night	11% 7% 3 8% 5% 5% 5% 4 6% 7% 41%	3087
August	1st to 10th	Night	13% 7% 3 9% 5% 4 6% 4 7% 8% 35%	2825
	11th to 20th	Night	15% 7% 3 5% 4 4 4 3 5% 7% 42%	2785
	21st to end	Night	9% 4 2 6% 4 5% 5% 5% 6% 9% 44%	3302
September	1st to 10th	Night	13% 6% 1 4 4 3 5% 4 5% 6% 49%	1900
	11th to 20th	Night	10% 4 2 4 3 4 5% 3 5% 9% 51%	2085
	21st to end	Night	16% 8% 3 6% 4 4 4 4 5% 6% 40%	2090
October	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 4 7% 46%	2279
	11th to 20th	Night	18% 8% 2 6% 5% 4 4 4 4 6% 40%	2280
	21st to end	Night	23% 8% 2 6% 3 3 4 3 5% 6% 36%	2508
November	1st to 10th	Night	14% 8% 3 6% 4 3 3 3 5% 7% 44%	2426
	11th to 20th	Night	19% 12% 3 7% 5% 4 4 4 5% 6% 32%	2730
	21st to end	Night	20% 14% 4 7% 5% 4 4 3 5% 5% 29%	2800
December	1st to 10th	Night	20% 16% 10% 13% 5% 4 3 3 5% 5% 18%	4580
	11th to 20th	Night	22% 17% 7% 10% 4 4 3 3 3 5% 22%	5205
	21st to end	Night	25% 18% 5% 10% 5% 4 4 3 4 5% 16%	6996

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	74% 5% 9% 9% 4	4039
	11th to 20th	Day	77% 3 7% 9% 3 2	4060
	21st to end	Day	73% 5% 7% 10% 5%	4466
February	1st to 10th	Day	67% 4 8% 14% 6% 1	1800
	11th to 20th	Day	64% 5% 10% 14% 6%	1762
	21st to end	Day	61% 5% 12% 15% 7% 1	1651
March	1st to 10th	Day	54% 6% 10% 22% 8% 1	4935
	11th to 20th	Day	47% 5% 13% 24% 9% 2	4980
	21st to end	Day	53% 5% 9% 20% 12% 1	5465
April	1st to 10th	Day	53% 6% 11% 18% 11% 1	2304
	11th to 20th	Day	50% 7% 10% 18% 13% 2	2417
	21st to end	Day	50% 6% 10% 22% 10% 2	2600
May	1st to 10th	Day	55% 7% 11% 17% 8% 3	5897
	11th to 20th	Day	50% 8% 11% 21% 9% 1	5865
	21st to end	Day	45% 8% 14% 21% 9% 3	6813
June	1st to 10th	Day	44% 9% 13% 22% 11% 1	2786
	11th to 20th	Day	43% 7% 14% 22% 12% 1	2660
	21st to end	Day	41% 8% 12% 25% 12% 1	2660
July	1st to 10th	Day	40% 7% 12% 23% 14% 3	4246
	11th to 20th	Day	37% 6% 12% 28% 16%	4051
	21st to end	Day	44% 7% 12% 20% 17% 1	4324
August	1st to 10th	Day	48% 8% 14% 21% 9%	4091
	11th to 20th	Day	42% 7% 12% 28% 10% 1	4083
	21st to end	Day	37% 9% 12% 27% 13% 2	4321
September	1st to 10th	Day	39% 7% 10% 22% 19% 3	2280
	11th to 20th	Day	36% 7% 14% 26% 15% 1	2091
	21st to end	Day	49% 6% 11% 21% 13%	2090
October	1st to 10th	Day	31% 6% 11% 32% 19% 1	3160
	11th to 20th	Day	45% 6% 9% 22% 14% 4	3140
	21st to end	Day	38% 4 13% 27% 17%	3428
November	1st to 10th	Day	43% 6% 10% 22% 17% 2	1867
	11th to 20th	Day	54% 4 12% 18% 10% 2	1667
	21st to end	Day	61% 5% 11% 15% 6% 1	1600
December	1st to 10th	Day	68% 4 12% 11% 4	2600
	11th to 20th	Day	67% 4 11% 14% 4	2986
	21st to end	Day	73% 5% 9% 10% 3	3960
January	1st to 10th	Night	74% 4 7% 10% 3	5889
	11th to 20th	Night	74% 5% 9% 9% 3	5900
	21st to end	Night	70% 4 8% 12% 5% 1	6490
February	1st to 10th	Night	63% 5% 9% 17% 6%	2600
	11th to 20th	Night	62% 5% 10% 16% 7%	2535
	21st to end	Night	61% 6% 8% 14% 9% 1	1974
March	1st to 10th	Night	56% 4 10% 21% 9% 1	4918
	11th to 20th	Night	44% 5% 13% 27% 8% 3	4980
	21st to end	Night	50% 5% 10% 19% 15% 1	5467
April	1st to 10th	Night	53% 5% 9% 18% 13% 2	2095
	11th to 20th	Night	47% 6% 12% 17% 15% 3	1949
	21st to end	Night	44% 7% 11% 24% 12% 3	1800
May	1st to 10th	Night	59% 6% 9% 14% 9% 3	4060
	11th to 20th	Night	46% 8% 9% 24% 12% 1	4033
	21st to end	Night	44% 8% 12% 23% 11% 3	4045
June	1st to 10th	Night	37% 8% 14% 23% 17% 2	1598
	11th to 20th	Night	37% 9% 15% 22% 15% 2	1520
	21st to end	Night	36% 9% 13% 24% 16% 2	1520
July	1st to 10th	Night	41% 7% 10% 22% 18% 2	2599
	11th to 20th	Night	35% 7% 15% 26% 16% 1	2786
	21st to end	Night	41% 7% 11% 17% 22% 3	2988
August	1st to 10th	Night	46% 8% 13% 21% 11% 1	2814
	11th to 20th	Night	40% 7% 10% 28% 15% 1	2812
	21st to end	Night	34% 8% 13% 29% 13% 2	3302
September	1st to 10th	Night	34% 7% 11% 23% 20% 5%	1900
	11th to 20th	Night	29% 8% 13% 26% 23% 1	2085
	21st to end	Night	43% 6% 11% 21% 17% 1	2090
October	1st to 10th	Night	35% 5% 9% 26% 23% 2	3799
	11th to 20th	Night	39% 5% 11% 23% 15% 8%	3779
	21st to end	Night	36% 4 9% 29% 20% 2	4120
November	1st to 10th	Night	41% 5% 12% 23% 17% 3	2426
	11th to 20th	Night	53% 5% 10% 19% 10% 3	2730
	21st to end	Night	57% 5% 11% 20% 6% 1	2800
December	1st to 10th	Night	69% 4 11% 13% 3	4580
	11th to 20th	Night	66% 4 13% 14% 3	5208
	21st to end	Night	70% 5% 10% 12% 2	6996

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	30% 30% 24% 12% 3 1	297
	11th to 20th	Day	32% 28% 30% 8% 1	300
	21st to end	Day	27% 32% 29% 9% 3 1	330
February	1st to 10th	Day	34% 21% 35% 9% 1	300
	11th to 20th	Day	36% 27% 28% 7% 1	300
	21st to end	Day	36% 24% 31% 9%	275
March	1st to 10th	Day	28% 22% 29% 17% 3	500
	11th to 20th	Day	32% 19% 30% 13% 4 1	500
	21st to end	Day	31% 20% 28% 16% 4 1	550
April	1st to 10th	Day	31% 19% 26% 16% 7% 1	500
	11th to 20th	Day	24% 21% 27% 17% 8% 3	492
	21st to end	Day	28% 16% 31% 17% 6% 2	500
May	1st to 10th	Day	26% 19% 27% 18% 7% 3	503
	11th to 20th	Day	21% 16% 30% 20% 10% 4	527
	21st to end	Day	17% 9% 27% 26% 17% 5%	573
June	1st to 10th	Day	15% 11% 31% 26% 13% 4	526
	11th to 20th	Day	17% 12% 25% 26% 16% 4	490
	21st to end	Day	15% 10% 32% 28% 13% 3	490
July	1st to 10th	Day	11% 7% 21% 30% 22% 9%	485
	11th to 20th	Day	13% 7% 26% 26% 20% 8%	484
	21st to end	Day	13% 6% 25% 30% 18% 8%	532
August	1st to 10th	Day	10% 6% 24% 31% 20% 9%	486
	11th to 20th	Day	14% 6% 23% 29% 17% 10%	479
	21st to end	Day	12% 5% 23% 28% 22% 11%	539
September	1st to 10th	Day	16% 8% 22% 28% 19% 8%	490
	11th to 20th	Day	11% 5% 19% 31% 22% 11%	490
	21st to end	Day	23% 11% 24% 23% 14% 4	490
October	1st to 10th	Day	17% 9% 28% 24% 18% 4	490
	11th to 20th	Day	22% 16% 29% 22% 8% 2	490
	21st to end	Day	29% 15% 31% 18% 7%	539
November	1st to 10th	Day	19% 18% 33% 16% 11% 2	405
	11th to 20th	Day	30% 18% 33% 14% 6% 1	233
	21st to end	Day	28% 22% 39% 10% 2	200
December	1st to 10th	Day	31% 26% 29% 10% 4 2	200
	11th to 20th	Day	35% 20% 32% 12% 2	200
	21st to end	Day	35% 19% 30% 14% 2	220
January	1st to 10th	Night	27% 23% 32% 16% 3	800
	11th to 20th	Night	31% 18% 31% 18% 3	800
	21st to end	Night	26% 20% 31% 20% 3	880
February	1st to 10th	Night	28% 17% 29% 24% 2	800
	11th to 20th	Night	31% 18% 34% 17% 1	783
	21st to end	Night	29% 16% 34% 18% 3	660
March	1st to 10th	Night	26% 17% 32% 23% 3	800
	11th to 20th	Night	25% 19% 28% 23% 5% 1	800
	21st to end	Night	24% 16% 33% 22% 5% 1	880
April	1st to 10th	Night	25% 16% 30% 24% 5%	800
	11th to 20th	Night	22% 13% 32% 23% 9% 1	765
	21st to end	Night	19% 10% 34% 31% 6%	600
May	1st to 10th	Night	22% 11% 25% 32% 9% 1	600
	11th to 20th	Night	20% 8% 28% 31% 13% 1	591
	21st to end	Night	14% 3 22% 36% 22% 3	487
June	1st to 10th	Night	11% 4 27% 39% 19% 1	400
	11th to 20th	Night	12% 4 24% 39% 19% 1	380
	21st to end	Night	10% 3 28% 37% 21% 1	380
July	1st to 10th	Night	9% 2 20% 42% 22% 6%	437
	11th to 20th	Night	8% 3 20% 36% 28% 4	552
	21st to end	Night	11% 3 15% 42% 27% 2	624
August	1st to 10th	Night	10% 1 17% 42% 27% 2	567
	11th to 20th	Night	10% 4 15% 38% 29% 4	564
	21st to end	Night	12% 3 21% 34% 25% 6%	727
September	1st to 10th	Night	16% 3 19% 33% 26% 4	760
	11th to 20th	Night	11% 3 17% 34% 31% 3	760
	21st to end	Night	19% 8% 24% 26% 19% 4	760
October	1st to 10th	Night	18% 7% 23% 29% 22% 2	760
	11th to 20th	Night	22% 11% 29% 26% 11% 1	760
	21st to end	Night	27% 12% 26% 27% 8%	836
November	1st to 10th	Night	18% 10% 28% 31% 12%	780
	11th to 20th	Night	27% 15% 27% 23% 7% 1	800
	21st to end	Night	28% 16% 29% 22% 6%	800
December	1st to 10th	Night	31% 17% 28% 20% 4	800
	11th to 20th	Night	28% 19% 30% 21% 3	800
	21st to end	Night	29% 15% 32% 22% 1	880

Page generated at 2025-06-07 10:28:12. Version ac07

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