Quiet Pond Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quiet Pond Observatory clear sky chart from 2005-11-06 to 2026-06-16.

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	14% 6% 2 5% 4 4 4 4 6% 8% 45%	137676
	Night	15% 6% 2 6% 4 4 4 4 5% 7% 43%	134355
Transparency	Day	25% 36% 8% 17% 12% 2	141266
	Night	26% 36% 8% 16% 12% 3	138836
Seeing	Day	16% 8% 24% 27% 19% 7%	17079
	Night	17% 9% 29% 29% 14% 2	26529

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	13% 5% 2 5% 4 3 4 3 5% 6% 49%	4661
	11th to 20th	Day	15% 8% 3 7% 3 3 2 2 3 4 50%	5177
	21st to end	Day	14% 5% 2 5% 4 4 4 3 5% 6% 47%	5780
February	1st to 10th	Day	15% 6% 2 6% 4 4 5% 4 5% 8% 41%	1890
	11th to 20th	Day	18% 8% 3 4 4 3 4 2 6% 7% 41%	1960
	21st to end	Day	18% 9% 2 6% 4 3 3 3 4 6% 41%	1730
March	1st to 10th	Day	18% 5% 1 4 3 3 4 3 5% 7% 48%	4785
	11th to 20th	Day	11% 7% 2 5% 4 4 4 3 5% 6% 50%	5090
	21st to end	Day	17% 5% 2 5% 4 4 4 3 5% 7% 44%	5806
April	1st to 10th	Day	15% 6% 2 5% 3 4 4 4 6% 7% 44%	2520
	11th to 20th	Day	12% 6% 2 5% 3 3 4 4 5% 7% 48%	2494
	21st to end	Day	16% 6% 2 5% 3 3 4 4 5% 8% 44%	2520
May	1st to 10th	Day	19% 7% 2 6% 4 3 4 4 5% 8% 38%	7311
	11th to 20th	Day	17% 6% 2 5% 4 4 4 4 6% 8% 41%	8221
	21st to end	Day	22% 6% 2 6% 3 3 4 3 5% 7% 40%	9045
June	1st to 10th	Day	9% 4 2 5% 5% 3 5% 5% 7% 10% 45%	2940
	11th to 20th	Day	10% 4 2 5% 4 4 4 4 7% 10% 44%	2870
	21st to end	Day	9% 4 1 4 3 3 5% 4 7% 11% 49%	2800
July	1st to 10th	Day	7% 4 2 6% 4 4 5% 5% 7% 10% 46%	6360
	11th to 20th	Day	9% 6% 2 7% 4 5% 6% 6% 8% 11% 35%	6360
	21st to end	Day	8% 5% 2 5% 4 5% 5% 5% 7% 10% 44%	6475
August	1st to 10th	Day	15% 6% 2 6% 4 3 5% 4 8% 10% 37%	4234
	11th to 20th	Day	11% 4 2 6% 5% 4 4 4 6% 9% 45%	3912
	21st to end	Day	8% 4 2 5% 4 4 4 4 6% 8% 51%	4312
September	1st to 10th	Day	13% 4 2 5% 4 4 4 3 5% 8% 49%	2400
	11th to 20th	Day	11% 6% 1 5% 3 3 4 2 5% 7% 51%	2400
	21st to end	Day	18% 8% 2 6% 4 3 4 4 5% 7% 38%	2139
October	1st to 10th	Day	16% 5% 1 5% 2 3 3 3 5% 7% 50%	2000
	11th to 20th	Day	16% 5% 2 4 2 3 3 3 5% 6% 52%	2000
	21st to end	Day	14% 6% 2 5% 3 3 3 3 5% 6% 50%	2200
November	1st to 10th	Day	12% 6% 1 4 3 3 4 2 5% 7% 53%	1872
	11th to 20th	Day	13% 5% 2 4 4 4 4 4 5% 6% 49%	1890
	21st to end	Day	14% 6% 2 5% 5% 3 4 3 5% 5% 48%	1724
December	1st to 10th	Day	12% 5% 3 6% 4 3 3 4 5% 8% 48%	2680
	11th to 20th	Day	18% 8% 2 6% 3 3 3 3 4 7% 44%	3070
	21st to end	Day	13% 7% 2 6% 4 4 4 3 5% 7% 43%	4048
January	1st to 10th	Night	13% 7% 2 5% 4 4 5% 3 5% 7% 44%	8233
	11th to 20th	Night	14% 7% 2 6% 3 3 3 2 4 5% 50%	7768
	21st to end	Night	14% 7% 2 5% 3 4 3 3 4 6% 48%	8401
February	1st to 10th	Night	16% 7% 2 6% 4 4 4 3 5% 7% 41%	2730
	11th to 20th	Night	20% 7% 3 5% 3 4 3 3 5% 6% 42%	2545
	21st to end	Night	17% 8% 2 6% 4 3 4 3 5% 6% 43%	2076
March	1st to 10th	Night	16% 7% 2 5% 3 3 3 3 4 5% 48%	5271
	11th to 20th	Night	10% 5% 2 4 3 4 4 3 6% 7% 51%	5090
	21st to end	Night	14% 7% 2 6% 4 4 4 3 5% 6% 45%	5367
April	1st to 10th	Night	16% 7% 2 5% 4 4 4 3 4 7% 42%	2100
	11th to 20th	Night	13% 6% 2 6% 5% 4 4 4 5% 7% 45%	2075
	21st to end	Night	18% 5% 2 4 4 3 4 3 6% 7% 45%	2100
May	1st to 10th	Night	18% 7% 3 7% 5% 5% 5% 5% 6% 7% 33%	5583
	11th to 20th	Night	19% 6% 2 6% 4 4 4 4 5% 8% 37%	4639
	21st to end	Night	24% 7% 3 7% 3 4 4 3 4 7% 34%	5108
June	1st to 10th	Night	10% 5% 3 6% 5% 4 4 3 6% 9% 46%	1680
	11th to 20th	Night	10% 6% 3 6% 5% 5% 4 4 8% 9% 40%	1640
	21st to end	Night	10% 4 2 5% 5% 5% 4 4 7% 11% 42%	1600
July	1st to 10th	Night	9% 5% 2 7% 5% 5% 6% 5% 8% 9% 39%	3598
	11th to 20th	Night	12% 6% 3 8% 6% 5% 5% 5% 8% 10% 32%	3597
	21st to end	Night	10% 6% 2 6% 5% 4 5% 5% 6% 9% 42%	4371
August	1st to 10th	Night	18% 6% 3 6% 4 5% 6% 4 7% 10% 32%	2915
	11th to 20th	Night	11% 7% 3 7% 5% 5% 6% 4 7% 8% 36%	3104
	21st to end	Night	9% 5% 2 6% 4 4 5% 3 6% 9% 47%	3586
September	1st to 10th	Night	13% 6% 2 5% 5% 4 4 3 6% 7% 46%	2000
	11th to 20th	Night	11% 4 2 5% 4 4 4 3 4 8% 50%	2000
	21st to end	Night	19% 7% 3 6% 4 4 4 3 5% 6% 38%	2257
October	1st to 10th	Night	17% 7% 2 6% 3 3 3 3 4 6% 45%	2400
	11th to 20th	Night	16% 5% 2 5% 3 2 3 3 5% 6% 51%	2400
	21st to end	Night	17% 5% 2 4 4 3 3 3 4 6% 50%	2640
November	1st to 10th	Night	11% 5% 2 5% 3 3 4 3 5% 6% 52%	2643
	11th to 20th	Night	16% 6% 2 5% 4 3 3 3 4 6% 47%	2730
	21st to end	Night	13% 5% 2 5% 4 4 4 4 5% 6% 48%	2893
December	1st to 10th	Night	11% 5% 2 5% 3 4 4 3 5% 7% 50%	4720
	11th to 20th	Night	21% 6% 2 5% 4 3 4 3 6% 7% 40%	5345
	21st to end	Night	15% 7% 2 6% 4 4 4 4 6% 7% 40%	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	30% 21% 5% 22% 18% 3	4662
	11th to 20th	Day	31% 21% 3 18% 19% 7%	5177
	21st to end	Day	30% 23% 7% 28% 10% 2	5780
February	1st to 10th	Day	18% 60% 7% 9% 5% 1	1890
	11th to 20th	Day	20% 58% 4 9% 8% 1	1969
	21st to end	Day	19% 59% 5% 9% 7% 1	1730
March	1st to 10th	Day	29% 30% 5% 15% 14% 7%	4785
	11th to 20th	Day	23% 29% 7% 22% 15% 4	5090
	21st to end	Day	29% 29% 7% 13% 16% 6%	5806
April	1st to 10th	Day	18% 60% 6% 8% 8% 2	2520
	11th to 20th	Day	15% 61% 6% 10% 7% 1	2494
	21st to end	Day	16% 59% 5% 12% 7% 1	2520
May	1st to 10th	Day	36% 25% 10% 17% 11% 1	7343
	11th to 20th	Day	32% 25% 9% 23% 10% 1	8225
	21st to end	Day	37% 24% 7% 16% 13% 2	9061
June	1st to 10th	Day	15% 61% 5% 10% 8% 1	2940
	11th to 20th	Day	13% 63% 5% 10% 8% 1	2870
	21st to end	Day	10% 62% 8% 11% 9% 1	2800
July	1st to 10th	Day	25% 31% 19% 12% 11% 3	6290
	11th to 20th	Day	33% 32% 15% 15% 3 1	6285
	21st to end	Day	26% 29% 9% 19% 17% 1	6289
August	1st to 10th	Day	28% 38% 12% 18% 4	4221
	11th to 20th	Day	22% 38% 9% 24% 8%	3950
	21st to end	Day	17% 37% 9% 22% 15% 1	4312
September	1st to 10th	Day	16% 58% 7% 11% 7% 2	2400
	11th to 20th	Day	15% 58% 5% 11% 9% 2	2400
	21st to end	Day	24% 57% 5% 9% 4 1	2139
October	1st to 10th	Day	21% 36% 5% 12% 21% 4	3260
	11th to 20th	Day	12% 35% 4 20% 21% 8%	3240
	21st to end	Day	9% 35% 6% 24% 20% 7%	3538
November	1st to 10th	Day	17% 54% 7% 11% 8% 3	1872
	11th to 20th	Day	14% 55% 4 13% 12% 2	1890
	21st to end	Day	16% 54% 4 17% 8% 1	1724
December	1st to 10th	Day	24% 35% 13% 17% 8% 3	2680
	11th to 20th	Day	29% 32% 8% 21% 7% 2	3066
	21st to end	Day	30% 28% 12% 17% 13% 1	4048
January	1st to 10th	Night	32% 22% 8% 20% 15% 3	8234
	11th to 20th	Night	29% 21% 6% 19% 18% 8%	7768
	21st to end	Night	30% 23% 5% 24% 16% 2	8401
February	1st to 10th	Night	18% 60% 6% 9% 5% 1	2730
	11th to 20th	Night	19% 57% 3 9% 10% 1	2547
	21st to end	Night	18% 59% 5% 10% 6% 3	2076
March	1st to 10th	Night	31% 30% 5% 17% 9% 9%	5271
	11th to 20th	Night	21% 30% 10% 20% 14% 6%	5090
	21st to end	Night	29% 29% 7% 14% 18% 3	5367
April	1st to 10th	Night	18% 59% 5% 9% 8% 1	2100
	11th to 20th	Night	16% 60% 5% 10% 7% 2	2075
	21st to end	Night	17% 60% 5% 9% 8% 1	2100
May	1st to 10th	Night	39% 26% 10% 17% 8% 1	5613
	11th to 20th	Night	35% 25% 11% 20% 9%	4640
	21st to end	Night	42% 24% 7% 13% 12% 2	5115
June	1st to 10th	Night	16% 60% 4 9% 10% 1	1680
	11th to 20th	Night	16% 62% 5% 11% 6%	1640
	21st to end	Night	13% 61% 6% 11% 7% 1	1600
July	1st to 10th	Night	31% 31% 14% 12% 11% 1	3560
	11th to 20th	Night	36% 30% 17% 13% 3	3552
	21st to end	Night	29% 28% 11% 17% 15%	4243
August	1st to 10th	Night	34% 39% 12% 12% 4	2904
	11th to 20th	Night	26% 39% 8% 21% 6%	3132
	21st to end	Night	20% 37% 6% 21% 16% 1	3586
September	1st to 10th	Night	16% 58% 7% 12% 6% 2	2000
	11th to 20th	Night	15% 58% 3 12% 10% 2	2000
	21st to end	Night	24% 58% 5% 8% 5%	2257
October	1st to 10th	Night	27% 37% 6% 13% 14% 3	3920
	11th to 20th	Night	12% 36% 8% 13% 26% 7%	3899
	21st to end	Night	10% 35% 7% 23% 19% 6%	4252
November	1st to 10th	Night	16% 54% 6% 11% 9% 3	2643
	11th to 20th	Night	17% 54% 4 10% 12% 3	2730
	21st to end	Night	15% 55% 5% 14% 9% 1	2893
December	1st to 10th	Night	21% 35% 10% 21% 12% 2	4720
	11th to 20th	Night	31% 32% 9% 13% 11% 4	5348
	21st to end	Night	32% 29% 10% 15% 14% 1	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	17% 18% 39% 18% 8%	220
	11th to 20th	Day	18% 20% 35% 23% 4	311
	21st to end	Day	18% 15% 38% 23% 6% 1	363
February	1st to 10th	Day	19% 11% 41% 21% 8%	330
	11th to 20th	Day	25% 14% 40% 18% 3	448
	21st to end	Day	24% 12% 35% 23% 7%	446
March	1st to 10th	Day	18% 16% 34% 23% 9% 1	540
	11th to 20th	Day	19% 15% 32% 24% 9% 2	540
	21st to end	Day	20% 10% 34% 29% 5% 2	594
April	1st to 10th	Day	19% 11% 35% 23% 10% 2	540
	11th to 20th	Day	14% 14% 30% 25% 13% 5%	532
	21st to end	Day	19% 10% 27% 27% 15% 2	540
May	1st to 10th	Day	20% 8% 29% 28% 13% 2	543
	11th to 20th	Day	18% 6% 26% 29% 16% 5%	567
	21st to end	Day	19% 4 18% 26% 24% 8%	617
June	1st to 10th	Day	10% 4 22% 28% 26% 11%	570
	11th to 20th	Day	12% 4 18% 27% 27% 11%	550
	21st to end	Day	9% 3 15% 33% 28% 11%	530
July	1st to 10th	Day	9% 2 9% 30% 34% 15%	525
	11th to 20th	Day	5% 1 6% 35% 38% 15%	524
	21st to end	Day	9% 2 11% 31% 34% 12%	576
August	1st to 10th	Day	12% 2 9% 30% 34% 13%	526
	11th to 20th	Day	11% 2 11% 31% 32% 13%	519
	21st to end	Day	8% 2 14% 29% 31% 16%	583
September	1st to 10th	Day	17% 3 14% 24% 28% 14%	530
	11th to 20th	Day	14% 4 13% 28% 30% 12%	530
	21st to end	Day	24% 6% 19% 29% 18% 4	530
October	1st to 10th	Day	18% 5% 16% 28% 22% 11%	530
	11th to 20th	Day	17% 8% 26% 28% 16% 5%	530
	21st to end	Day	15% 8% 30% 29% 12% 5%	583
November	1st to 10th	Day	15% 8% 33% 26% 13% 5%	436
	11th to 20th	Day	12% 15% 34% 29% 9% 1	430
	21st to end	Day	16% 15% 33% 22% 13% 2	264
December	1st to 10th	Day	19% 11% 34% 27% 7% 2	220
	11th to 20th	Day	19% 15% 32% 24% 10%	220
	21st to end	Day	20% 11% 31% 29% 9% 1	242
January	1st to 10th	Night	18% 17% 40% 22% 3	840
	11th to 20th	Night	21% 15% 33% 27% 4	840
	21st to end	Night	18% 15% 39% 25% 2	924
February	1st to 10th	Night	20% 12% 36% 29% 4	840
	11th to 20th	Night	23% 16% 39% 20% 1	823
	21st to end	Night	21% 14% 38% 24% 3	692
March	1st to 10th	Night	17% 14% 38% 25% 5%	840
	11th to 20th	Night	18% 14% 36% 24% 6% 2	840
	21st to end	Night	18% 9% 40% 27% 5% 1	924
April	1st to 10th	Night	20% 11% 38% 23% 7%	840
	11th to 20th	Night	15% 8% 35% 32% 10%	831
	21st to end	Night	19% 8% 32% 29% 11% 1	840
May	1st to 10th	Night	18% 8% 29% 32% 13% 1	757
	11th to 20th	Night	19% 6% 27% 33% 15% 1	414
	21st to end	Night	15% 5% 19% 36% 23% 2	455
June	1st to 10th	Night	11% 2 24% 38% 24% 2	420
	11th to 20th	Night	10% 4 22% 40% 24% 1	410
	21st to end	Night	11% 1 18% 44% 23% 3	400
July	1st to 10th	Night	10% 2 16% 35% 33% 4	390
	11th to 20th	Night	6% 1 10% 40% 37% 4	388
	21st to end	Night	9% 2 15% 40% 31% 4	627
August	1st to 10th	Night	11% 2 10% 41% 32% 3	597
	11th to 20th	Night	11% 3 14% 33% 33% 4	733
	21st to end	Night	12% 2 13% 35% 31% 7%	880
September	1st to 10th	Night	16% 3 15% 32% 29% 5%	800
	11th to 20th	Night	13% 4 13% 33% 32% 6%	800
	21st to end	Night	23% 5% 18% 31% 21% 3	800
October	1st to 10th	Night	20% 5% 21% 26% 22% 6%	800
	11th to 20th	Night	18% 8% 27% 29% 16% 2	800
	21st to end	Night	18% 10% 30% 27% 15% 1	880
November	1st to 10th	Night	14% 7% 32% 32% 13% 2	820
	11th to 20th	Night	19% 13% 31% 27% 9%	840
	21st to end	Night	16% 14% 34% 28% 8% 1	840
December	1st to 10th	Night	20% 14% 34% 23% 9% 1	840
	11th to 20th	Night	18% 12% 39% 25% 6%	840
	21st to end	Night	18% 10% 36% 31% 4	924

Page generated at 2026-06-13 02:31:44. Version ac07

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