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 2026-10-14.

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% 5% 4 5% 7% 31%	149082
	Night	18% 11% 4 9% 5% 4 4 3 5% 6% 31%	142625
Transparency	Day	51% 6% 11% 20% 11% 1	152686
	Night	52% 5% 11% 19% 11% 1	147091
Seeing	Day	22% 15% 28% 21% 11% 4	17207
	Night	22% 12% 27% 27% 11% 1	26858

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	18% 18% 7% 21% 5% 4 3 2 3 5% 13%	5240
	11th to 20th	Day	13% 20% 9% 19% 8% 6% 3 2 3 3 15%	5280
	21st to end	Day	19% 16% 6% 13% 10% 6% 3 2 4 4 16%	5780
February	1st to 10th	Day	20% 16% 5% 11% 7% 5% 3 2 4 5% 22%	1890
	11th to 20th	Day	17% 14% 7% 13% 5% 5% 4 3 5% 5% 22%	1843
	21st to end	Day	19% 15% 5% 10% 6% 3 4 3 4 6% 25%	1731
March	1st to 10th	Day	18% 11% 6% 9% 5% 4 3 3 4 6% 30%	5045
	11th to 20th	Day	13% 9% 4 8% 5% 5% 5% 3 5% 6% 36%	5090
	21st to end	Day	19% 10% 3 8% 5% 4 4 3 5% 6% 30%	5586
April	1st to 10th	Day	16% 13% 4 8% 4 5% 4 4 5% 7% 30%	2419
	11th to 20th	Day	17% 10% 3 8% 5% 5% 5% 4 5% 6% 33%	2539
	21st to end	Day	21% 9% 3 7% 4 4 4 4 4 7% 33%	2730
May	1st to 10th	Day	22% 8% 3 8% 5% 5% 5% 4 6% 6% 28%	7616
	11th to 20th	Day	18% 7% 3 8% 5% 5% 5% 4 5% 8% 32%	7626
	21st to end	Day	22% 7% 2 6% 4 4 4 4 5% 7% 34%	8868
June	1st to 10th	Day	14% 7% 3 6% 5% 5% 5% 4 7% 8% 35%	2940
	11th to 20th	Day	15% 6% 3 7% 5% 5% 5% 4 6% 9% 35%	2940
	21st to end	Day	14% 7% 2 7% 5% 5% 5% 4 6% 9% 38%	2940
July	1st to 10th	Day	12% 6% 2 7% 5% 5% 5% 4 6% 8% 41%	8041
	11th to 20th	Day	11% 6% 2 7% 5% 5% 5% 4 7% 11% 38%	7680
	21st to end	Day	14% 6% 2 7% 5% 5% 5% 4 6% 8% 37%	8340
August	1st to 10th	Day	19% 7% 3 8% 6% 5% 6% 4 6% 7% 29%	6014
	11th to 20th	Day	19% 7% 2 7% 5% 5% 6% 4 6% 8% 32%	5951
	21st to end	Day	8% 4 2 6% 5% 6% 6% 5% 7% 10% 40%	6292
September	1st to 10th	Day	14% 7% 2 5% 3 3 5% 3 5% 8% 45%	2520
	11th to 20th	Day	11% 6% 2 5% 4 5% 5% 3 6% 8% 44%	2311
	21st to end	Day	20% 7% 3 8% 5% 4 4 3 5% 6% 35%	2310
October	1st to 10th	Day	15% 5% 2 5% 4 3 5% 3 6% 8% 43%	2100
	11th to 20th	Day	19% 8% 2 8% 5% 5% 5% 3 5% 5% 35%	2030
	21st to end	Day	23% 10% 2 6% 4 4 4 3 5% 7% 32%	2200
November	1st to 10th	Day	12% 8% 3 7% 5% 5% 5% 4 4 6% 42%	1962
	11th to 20th	Day	17% 15% 3 7% 5% 4 4 3 5% 5% 31%	1750
	21st to end	Day	17% 16% 6% 10% 5% 4 4 4 4 5% 24%	1680
December	1st to 10th	Day	20% 14% 8% 16% 5% 3 3 3 4 4 20%	2680
	11th to 20th	Day	25% 17% 5% 11% 4 3 3 3 3 5% 22%	3070
	21st to end	Day	24% 21% 6% 11% 5% 4 4 3 4 5% 13%	4048
January	1st to 10th	Night	16% 18% 7% 20% 5% 4 4 3 3 4 14%	7635
	11th to 20th	Night	14% 17% 9% 17% 9% 6% 4 2 3 4 15%	7680
	21st to end	Night	20% 15% 6% 12% 8% 6% 4 2 3 4 21%	8401
February	1st to 10th	Night	21% 13% 4 10% 6% 4 4 3 5% 5% 24%	2730
	11th to 20th	Night	19% 13% 5% 12% 6% 5% 4 4 4 5% 24%	2663
	21st to end	Night	20% 13% 4 12% 5% 4 5% 3 4 5% 24%	2070
March	1st to 10th	Night	23% 11% 4 8% 4 3 3 2 4 5% 32%	5028
	11th to 20th	Night	15% 10% 4 7% 3 4 4 3 5% 7% 39%	5090
	21st to end	Night	19% 11% 3 8% 5% 4 3 3 4 5% 35%	5588
April	1st to 10th	Night	20% 12% 3 7% 5% 4 4 3 4 6% 33%	2200
	11th to 20th	Night	17% 8% 3 7% 5% 5% 4 4 5% 7% 35%	2048
	21st to end	Night	15% 9% 3 6% 5% 3 4 4 6% 8% 37%	1890
May	1st to 10th	Night	24% 10% 3 7% 5% 4 4 3 5% 6% 29%	5237
	11th to 20th	Night	16% 8% 3 7% 5% 4 4 4 5% 8% 37%	5234
	21st to end	Night	24% 7% 2 6% 4 3 4 3 5% 7% 35%	5268
June	1st to 10th	Night	10% 7% 3 6% 5% 4 4 4 6% 8% 44%	1680
	11th to 20th	Night	12% 5% 4 6% 4 5% 4 4 6% 8% 41%	1680
	21st to end	Night	11% 4 2 6% 5% 5% 5% 5% 6% 8% 43%	1680
July	1st to 10th	Night	14% 7% 2 7% 4 5% 4 4 5% 7% 41%	4912
	11th to 20th	Night	12% 6% 3 7% 5% 5% 5% 4 6% 9% 39%	5277
	21st to end	Night	13% 6% 2 7% 4 4 4 4 5% 7% 44%	5736
August	1st to 10th	Night	17% 8% 3 9% 5% 4 5% 4 6% 7% 31%	4135
	11th to 20th	Night	20% 7% 3 6% 4 4 4 3 5% 6% 37%	4095
	21st to end	Night	9% 4 2 6% 4 5% 6% 4 6% 9% 43%	4785
September	1st to 10th	Night	12% 5% 1 4 4 3 5% 4 6% 6% 49%	2100
	11th to 20th	Night	11% 4 2 4 3 3 5% 3 5% 9% 50%	2305
	21st to end	Night	17% 8% 4 6% 4 4 4 4 5% 6% 38%	2310
October	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 4 6% 48%	2519
	11th to 20th	Night	18% 7% 2 6% 5% 4 4 4 4 6% 40%	2437
	21st to end	Night	23% 8% 3 6% 3 3 4 3 4 6% 37%	2640
November	1st to 10th	Night	14% 8% 3 6% 4 3 4 3 5% 7% 44%	2550
	11th to 20th	Night	19% 12% 3 7% 5% 4 4 4 5% 6% 31%	2867
	21st to end	Night	21% 14% 4 7% 5% 4 3 3 5% 5% 28%	2940
December	1st to 10th	Night	19% 16% 10% 13% 5% 4 3 3 4 5% 18%	4720
	11th to 20th	Night	22% 17% 7% 10% 4 4 3 3 3 5% 22%	5345
	21st to end	Night	25% 18% 5% 11% 5% 4 4 3 4 5% 16%	7150

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	75% 4 9% 8% 3	5241
	11th to 20th	Day	76% 3 7% 9% 5% 1	5280
	21st to end	Day	72% 4 7% 12% 4	5780
February	1st to 10th	Day	66% 4 8% 15% 7%	1890
	11th to 20th	Day	64% 5% 10% 14% 6%	1852
	21st to end	Day	60% 5% 12% 16% 6% 1	1731
March	1st to 10th	Day	54% 6% 10% 22% 8% 1	5045
	11th to 20th	Day	48% 5% 13% 24% 9% 2	5090
	21st to end	Day	53% 5% 9% 20% 12% 1	5586
April	1st to 10th	Day	52% 6% 11% 18% 11% 1	2419
	11th to 20th	Day	50% 6% 10% 17% 13% 2	2539
	21st to end	Day	50% 6% 10% 22% 10% 2	2730
May	1st to 10th	Day	54% 6% 11% 19% 7% 2	7651
	11th to 20th	Day	48% 7% 12% 23% 10% 1	7630
	21st to end	Day	48% 7% 11% 18% 14% 3	8883
June	1st to 10th	Day	43% 9% 12% 22% 12% 1	2940
	11th to 20th	Day	44% 7% 14% 22% 12% 1	2940
	21st to end	Day	41% 8% 13% 25% 12% 1	2940
July	1st to 10th	Day	41% 6% 11% 26% 14% 2	7974
	11th to 20th	Day	39% 6% 12% 30% 12%	7611
	21st to end	Day	42% 7% 10% 22% 18% 1	8156
August	1st to 10th	Day	52% 8% 11% 17% 10% 2	6001
	11th to 20th	Day	48% 6% 13% 24% 8% 1	5990
	21st to end	Day	35% 9% 17% 27% 12% 1	6292
September	1st to 10th	Day	38% 6% 11% 23% 19% 3	2520
	11th to 20th	Day	37% 6% 14% 26% 16% 1	2311
	21st to end	Day	50% 5% 11% 20% 13%	2310
October	1st to 10th	Day	30% 6% 11% 32% 20% 1	3360
	11th to 20th	Day	44% 6% 10% 22% 14% 4	3270
	21st to end	Day	38% 4 12% 27% 17% 1	3538
November	1st to 10th	Day	43% 6% 11% 22% 17% 2	1962
	11th to 20th	Day	55% 4 12% 18% 10% 2	1750
	21st to end	Day	62% 5% 11% 16% 6% 1	1680
December	1st to 10th	Day	69% 4 12% 11% 4	2680
	11th to 20th	Day	67% 4 11% 14% 4	3066
	21st to end	Day	73% 5% 9% 10% 3	4048
January	1st to 10th	Night	74% 4 9% 10% 3	7636
	11th to 20th	Night	74% 5% 8% 10% 4	7680
	21st to end	Night	67% 4 8% 14% 6% 1	8401
February	1st to 10th	Night	62% 5% 9% 17% 6%	2730
	11th to 20th	Night	62% 5% 10% 16% 7%	2665
	21st to end	Night	61% 6% 8% 15% 9% 1	2070
March	1st to 10th	Night	56% 4 10% 21% 9% 1	5028
	11th to 20th	Night	44% 5% 13% 27% 8% 3	5090
	21st to end	Night	50% 5% 10% 19% 15% 1	5588
April	1st to 10th	Night	53% 5% 9% 19% 13% 2	2200
	11th to 20th	Night	47% 6% 13% 17% 14% 3	2048
	21st to end	Night	45% 7% 11% 23% 12% 3	1890
May	1st to 10th	Night	55% 6% 9% 17% 10% 3	5264
	11th to 20th	Night	45% 7% 10% 26% 11% 1	5235
	21st to end	Night	48% 6% 11% 20% 13% 2	5275
June	1st to 10th	Night	37% 7% 13% 23% 18% 2	1680
	11th to 20th	Night	38% 8% 15% 22% 15% 2	1680
	21st to end	Night	38% 8% 13% 23% 16% 1	1680
July	1st to 10th	Night	43% 6% 9% 23% 18% 1	4871
	11th to 20th	Night	40% 6% 15% 25% 13% 1	5226
	21st to end	Night	39% 6% 11% 18% 25% 2	5606
August	1st to 10th	Night	51% 7% 12% 18% 10% 2	4124
	11th to 20th	Night	47% 6% 12% 23% 12% 1	4122
	21st to end	Night	35% 7% 15% 29% 12% 2	4785
September	1st to 10th	Night	33% 7% 12% 24% 20% 5%	2100
	11th to 20th	Night	30% 7% 13% 28% 21% 1	2305
	21st to end	Night	46% 6% 11% 20% 16% 2	2310
October	1st to 10th	Night	34% 5% 8% 26% 24% 2	4039
	11th to 20th	Night	38% 5% 11% 22% 15% 8%	3936
	21st to end	Night	36% 4 9% 29% 21% 2	4252
November	1st to 10th	Night	41% 5% 12% 23% 17% 3	2550
	11th to 20th	Night	53% 5% 10% 20% 10% 3	2867
	21st to end	Night	58% 5% 11% 20% 6% 1	2940
December	1st to 10th	Night	69% 4 11% 13% 3	4720
	11th to 20th	Night	66% 4 13% 15% 3	5348
	21st to end	Night	70% 5% 10% 12% 2	7150

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% 25% 12% 3 1	327
	11th to 20th	Day	36% 27% 28% 7% 1	330
	21st to end	Day	29% 31% 28% 9% 3 1	363
February	1st to 10th	Day	33% 20% 35% 10% 2	330
	11th to 20th	Day	37% 27% 28% 7% 1	330
	21st to end	Day	34% 23% 35% 8%	300
March	1st to 10th	Day	30% 22% 29% 16% 3	540
	11th to 20th	Day	34% 20% 29% 12% 4 1	540
	21st to end	Day	32% 20% 28% 15% 4 1	594
April	1st to 10th	Day	31% 19% 26% 16% 6% 1	540
	11th to 20th	Day	25% 21% 28% 16% 7% 3	532
	21st to end	Day	29% 16% 31% 18% 5% 1	540
May	1st to 10th	Day	27% 20% 27% 17% 6% 3	543
	11th to 20th	Day	21% 16% 31% 20% 9% 4	567
	21st to end	Day	18% 9% 26% 26% 16% 5%	617
June	1st to 10th	Day	14% 12% 31% 25% 13% 4	570
	11th to 20th	Day	18% 14% 26% 24% 15% 4	570
	21st to end	Day	15% 9% 30% 28% 15% 3	570
July	1st to 10th	Day	11% 6% 21% 30% 23% 9%	565
	11th to 20th	Day	12% 7% 25% 28% 21% 8%	564
	21st to end	Day	13% 5% 25% 31% 17% 7%	620
August	1st to 10th	Day	11% 7% 25% 31% 18% 8%	566
	11th to 20th	Day	15% 6% 23% 30% 17% 9%	559
	21st to end	Day	11% 5% 25% 28% 21% 10%	627
September	1st to 10th	Day	15% 8% 22% 28% 19% 7%	570
	11th to 20th	Day	11% 5% 20% 31% 22% 11%	570
	21st to end	Day	24% 11% 25% 23% 14% 4	570
October	1st to 10th	Day	16% 9% 27% 25% 19% 4	570
	11th to 20th	Day	22% 16% 30% 21% 8% 2	542
	21st to end	Day	30% 15% 32% 17% 7%	583
November	1st to 10th	Day	20% 18% 33% 16% 10% 2	440
	11th to 20th	Day	32% 17% 31% 13% 5% 1	256
	21st to end	Day	30% 22% 36% 10% 2	220
December	1st to 10th	Day	32% 26% 29% 9% 3 1	220
	11th to 20th	Day	35% 20% 33% 10% 2	220
	21st to end	Day	37% 18% 29% 13% 2	242
January	1st to 10th	Night	28% 22% 32% 15% 2	840
	11th to 20th	Night	32% 18% 30% 17% 3	840
	21st to end	Night	27% 21% 30% 19% 3	924
February	1st to 10th	Night	27% 16% 29% 25% 2	840
	11th to 20th	Night	30% 18% 34% 17% 1	823
	21st to end	Night	29% 16% 34% 18% 3	692
March	1st to 10th	Night	27% 17% 31% 22% 3	840
	11th to 20th	Night	26% 18% 28% 22% 5% 1	840
	21st to end	Night	24% 16% 33% 21% 5% 1	924
April	1st to 10th	Night	25% 16% 29% 24% 5%	840
	11th to 20th	Night	22% 13% 33% 23% 9% 1	804
	21st to end	Night	20% 10% 33% 31% 6%	630
May	1st to 10th	Night	22% 11% 26% 32% 9% 1	630
	11th to 20th	Night	19% 8% 28% 31% 13%	621
	21st to end	Night	15% 3 23% 35% 21% 3	512
June	1st to 10th	Night	11% 3 27% 39% 19% 1	420
	11th to 20th	Night	12% 5% 25% 38% 18% 1	420
	21st to end	Night	10% 4 29% 36% 20% 2	420
July	1st to 10th	Night	9% 3 19% 41% 23% 6%	485
	11th to 20th	Night	9% 3 19% 35% 29% 4	612
	21st to end	Night	11% 3 15% 42% 26% 2	690
August	1st to 10th	Night	11% 1 18% 42% 26% 2	627
	11th to 20th	Night	11% 4 14% 38% 28% 3	624
	21st to end	Night	11% 3 21% 35% 24% 5%	803
September	1st to 10th	Night	15% 3 20% 34% 25% 3	840
	11th to 20th	Night	11% 3 16% 35% 30% 3	840
	21st to end	Night	20% 8% 23% 26% 18% 4	840
October	1st to 10th	Night	17% 7% 23% 30% 22% 2	840
	11th to 20th	Night	22% 10% 30% 26% 10% 1	813
	21st to end	Night	26% 13% 26% 27% 8%	880
November	1st to 10th	Night	18% 10% 28% 31% 12%	820
	11th to 20th	Night	28% 15% 27% 23% 6% 1	840
	21st to end	Night	28% 15% 29% 22% 5%	840
December	1st to 10th	Night	31% 17% 28% 20% 4	840
	11th to 20th	Night	28% 19% 30% 20% 3	840
	21st to end	Night	29% 15% 33% 22% 1	924

Page generated at 2026-10-11 05:06:27. Version ac07

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