Peddler Hill
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peddler Hill clear sky chart from 2005-11-06 to 2025-12-18.

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	6% 7% 2 3 2 2 2 2 3 5% 65%	135686
	Night	6% 7% 2 4 3 3 3 2 4 5% 61%	132766
Transparency	Day	24% 3 7% 19% 26% 22%	130654
	Night	27% 3 6% 18% 25% 20%	128779
Seeing	Day	15% 17% 32% 22% 10% 3	16567
	Night	13% 8% 22% 34% 20% 4	25964

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	8% 14% 3 4 2 2 3 3 5% 6% 50%	3639
	11th to 20th	Day	10% 9% 2 5% 3 3 2 2 3 5% 56%	3870
	21st to end	Day	11% 12% 3 5% 4 3 3 3 4 6% 46%	4510
February	1st to 10th	Day	15% 12% 3 5% 3 2 3 3 4 5% 46%	1800
	11th to 20th	Day	8% 13% 4 6% 3 3 4 2 3 7% 45%	1946
	21st to end	Day	12% 16% 4 6% 3 3 3 2 3 5% 43%	1650
March	1st to 10th	Day	7% 20% 9% 9% 3 3 3 3 5% 5% 32%	4518
	11th to 20th	Day	9% 15% 5% 4 2 3 3 2 4 6% 48%	4995
	21st to end	Day	11% 22% 5% 6% 3 3 3 2 4 5% 36%	5790
April	1st to 10th	Day	11% 13% 3 5% 3 3 3 3 5% 6% 45%	2400
	11th to 20th	Day	8% 13% 3 5% 3 3 3 2 4 6% 50%	2369
	21st to end	Day	10% 8% 2 3 2 2 3 3 5% 7% 54%	2400
May	1st to 10th	Day	6% 6% 2 3 2 2 2 1 3 5% 69%	5605
	11th to 20th	Day	3 7% 2 3 2 2 2 2 3 5% 69%	6179
	21st to end	Day	4 3 1 3 2 2 2 2 4 4 73%	6902
June	1st to 10th	Day	6% 5% 2 4 3 2 3 3 5% 6% 62%	2800
	11th to 20th	Day	3 2 1 2 1 2 2 2 3 5% 77%	2800
	21st to end	Day	2 2 1 2 1 2 2 2 3 3 80%	2800
July	1st to 10th	Day	1 1 1 1 1 2 92%	6319
	11th to 20th	Day	1 1 2 1 1 2 2 2 3 85%	6320
	21st to end	Day	1 1 1 2 1 1 2 2 3 4 83%	6580
August	1st to 10th	Day	1 1 1 2 1 2 2 1 2 3 84%	5718
	11th to 20th	Day	1 1 1 1 1 1 2 2 90%	5364
	21st to end	Day	2 1 1 3 2 2 2 2 3 4 78%	5984
September	1st to 10th	Day	2 1 1 2 2 2 1 3 3 84%	2400
	11th to 20th	Day	4 3 1 3 2 2 2 2 4 4 72%	2383
	21st to end	Day	5% 4 1 3 1 2 2 2 3 4 75%	2200
October	1st to 10th	Day	5% 3 1 3 2 2 2 3 4 5% 70%	3290
	11th to 20th	Day	6% 2 1 3 2 2 2 2 3 3 75%	3261
	21st to end	Day	5% 5% 1 4 3 3 3 2 4 6% 64%	3534
November	1st to 10th	Day	10% 7% 3 2 3 4 3 4 5% 7% 53%	1854
	11th to 20th	Day	9% 8% 2 4 3 3 4 4 4 7% 52%	1890
	21st to end	Day	9% 9% 2 4 2 3 3 3 5% 6% 54%	1828
December	1st to 10th	Day	7% 4 1 3 2 3 4 4 6% 8% 59%	2700
	11th to 20th	Day	17% 13% 4 6% 4 4 4 3 5% 6% 36%	3084
	21st to end	Day	15% 12% 3 5% 4 3 4 4 6% 9% 35%	4004
January	1st to 10th	Night	6% 9% 3 6% 3 4 4 4 6% 8% 48%	6306
	11th to 20th	Night	11% 9% 3 5% 3 3 4 3 4 5% 52%	6083
	21st to end	Night	8% 13% 3 5% 4 4 4 3 4 6% 48%	6468
February	1st to 10th	Night	13% 11% 3 6% 3 3 3 2 4 6% 47%	2600
	11th to 20th	Night	8% 13% 3 6% 4 3 4 3 5% 6% 45%	2340
	21st to end	Night	10% 12% 3 7% 3 2 2 3 5% 4 48%	1980
March	1st to 10th	Night	7% 19% 7% 7% 3 3 3 3 4 6% 37%	5376
	11th to 20th	Night	10% 15% 4 6% 3 2 2 2 3 5% 48%	5000
	21st to end	Night	10% 19% 4 6% 4 3 3 3 5% 7% 36%	5184
April	1st to 10th	Night	9% 10% 3 5% 3 3 3 3 4 6% 48%	2000
	11th to 20th	Night	8% 10% 2 5% 4 3 3 3 4 6% 53%	1979
	21st to end	Night	7% 9% 1 3 3 3 3 3 5% 6% 58%	2000
May	1st to 10th	Night	3 3 2 4 2 2 2 2 3 5% 72%	4386
	11th to 20th	Night	2 4 1 2 2 2 3 2 3 5% 73%	3713
	21st to end	Night	3 3 1 2 2 2 2 1 3 4 78%	3972
June	1st to 10th	Night	5% 5% 1 3 2 3 3 2 5% 5% 66%	1600
	11th to 20th	Night	2 1 1 1 1 1 2 2 3 3 83%	1600
	21st to end	Night	2 2 1 1 2 2 2 2 2 2 82%	1600
July	1st to 10th	Night	1 1 1 1 1 1 94%	3640
	11th to 20th	Night	2 2 1 2 2 2 2 1 2 3 81%	3640
	21st to end	Night	2 2 1 2 2 2 2 2 3 5% 77%	4281
August	1st to 10th	Night	2 2 1 2 1 1 2 2 2 3 82%	4095
	11th to 20th	Night	1 1 1 1 1 1 1 2 2 90%	4506
	21st to end	Night	2 2 1 3 2 2 2 2 2 3 80%	5015
September	1st to 10th	Night	2 1 1 1 1 1 1 2 4 86%	2000
	11th to 20th	Night	3 2 2 1 2 2 2 3 5% 77%	2015
	21st to end	Night	3 2 1 2 2 2 2 2 2 5% 77%	2200
October	1st to 10th	Night	3 3 1 2 2 2 2 2 3 3 77%	3907
	11th to 20th	Night	3 2 1 3 1 2 2 2 3 4 78%	3897
	21st to end	Night	7% 3 1 3 3 3 3 3 4 5% 65%	4274
November	1st to 10th	Night	9% 8% 2 3 2 3 2 2 5% 6% 58%	2665
	11th to 20th	Night	8% 7% 1 3 4 3 4 3 5% 8% 55%	2730
	21st to end	Night	9% 8% 2 4 3 3 3 3 4 5% 57%	2788
December	1st to 10th	Night	8% 5% 1 3 3 2 3 3 4 6% 62%	4700
	11th to 20th	Night	14% 12% 3 6% 4 4 5% 4 7% 9% 32%	5274
	21st to end	Night	14% 12% 4 7% 5% 4 4 3 5% 7% 34%	6952

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	36% 4 13% 18% 20% 9%	3639
	11th to 20th	Day	34% 2 7% 13% 26% 18%	3870
	21st to end	Day	40% 4 7% 13% 18% 17%	4510
February	1st to 10th	Day	42% 3 8% 18% 17% 13%	1800
	11th to 20th	Day	41% 4 7% 18% 22% 8%	1956
	21st to end	Day	45% 4 6% 19% 17% 9%	1650
March	1st to 10th	Day	51% 5% 8% 12% 16% 7%	4518
	11th to 20th	Day	39% 3 11% 27% 16% 3	4995
	21st to end	Day	49% 6% 11% 21% 11% 2	5790
April	1st to 10th	Day	39% 4 13% 21% 18% 4	2400
	11th to 20th	Day	34% 6% 11% 24% 17% 7%	2372
	21st to end	Day	29% 4 15% 29% 20% 3	2400
May	1st to 10th	Day	20% 3 9% 29% 28% 11%	5605
	11th to 20th	Day	19% 3 8% 34% 30% 6%	6182
	21st to end	Day	14% 4 7% 33% 33% 7%	6904
June	1st to 10th	Day	23% 5% 10% 27% 27% 8%	2800
	11th to 20th	Day	12% 3 7% 23% 35% 19%	2800
	21st to end	Day	10% 3 4 14% 36% 33%	2800
July	1st to 10th	Day	3 1 1 5% 22% 68%	6251
	11th to 20th	Day	7% 1 2 8% 16% 66%	6245
	21st to end	Day	8% 2 3 16% 33% 39%	6390
August	1st to 10th	Day	11% 2 2 9% 30% 46%	4158
	11th to 20th	Day	5% 2 2 7% 38% 46%	3880
	21st to end	Day	8% 1 2 11% 43% 34%	4311
September	1st to 10th	Day	8% 2 2 12% 37% 39%	2400
	11th to 20th	Day	16% 3 4 21% 38% 17%	2383
	21st to end	Day	15% 3 4 20% 35% 23%	2200
October	1st to 10th	Day	17% 3 4 10% 36% 30%	3290
	11th to 20th	Day	16% 2 4 20% 40% 19%	3261
	21st to end	Day	22% 3 5% 23% 33% 14%	3534
November	1st to 10th	Day	31% 4 8% 22% 23% 13%	1854
	11th to 20th	Day	32% 4 10% 18% 24% 12%	1890
	21st to end	Day	31% 3 7% 20% 27% 13%	1828
December	1st to 10th	Day	24% 4 8% 21% 26% 17%	2700
	11th to 20th	Day	50% 4 8% 12% 16% 10%	3084
	21st to end	Day	45% 5% 12% 16% 15% 7%	4004
January	1st to 10th	Night	32% 5% 14% 23% 18% 8%	6306
	11th to 20th	Night	35% 4 6% 11% 26% 19%	6083
	21st to end	Night	38% 4 7% 10% 17% 23%	6468
February	1st to 10th	Night	41% 3 6% 17% 19% 15%	2600
	11th to 20th	Night	39% 4 7% 19% 21% 10%	2341
	21st to end	Night	39% 3 7% 21% 20% 10%	1980
March	1st to 10th	Night	49% 3 7% 14% 19% 9%	5376
	11th to 20th	Night	40% 3 6% 26% 20% 4	5000
	21st to end	Night	47% 6% 11% 21% 12% 3	5184
April	1st to 10th	Night	36% 6% 12% 21% 20% 6%	2000
	11th to 20th	Night	32% 6% 11% 24% 18% 9%	1979
	21st to end	Night	27% 5% 10% 34% 19% 5%	2000
May	1st to 10th	Night	15% 4 9% 33% 28% 10%	4383
	11th to 20th	Night	14% 3 8% 31% 34% 10%	3713
	21st to end	Night	12% 3 8% 29% 38% 10%	3972
June	1st to 10th	Night	20% 5% 10% 26% 29% 11%	1600
	11th to 20th	Night	9% 3 6% 25% 35% 22%	1600
	21st to end	Night	10% 2 4 14% 36% 34%	1600
July	1st to 10th	Night	3 1 1 4 23% 68%	3600
	11th to 20th	Night	11% 2 2 6% 19% 60%	3592
	21st to end	Night	11% 2 3 16% 25% 43%	4159
August	1st to 10th	Night	13% 2 3 8% 28% 46%	2977
	11th to 20th	Night	6% 2 2 8% 32% 51%	3256
	21st to end	Night	9% 1 1 12% 39% 38%	3608
September	1st to 10th	Night	6% 1 2 11% 38% 42%	2000
	11th to 20th	Night	12% 2 4 22% 38% 20%	2015
	21st to end	Night	12% 3 3 22% 34% 25%	2200
October	1st to 10th	Night	14% 2 4 11% 32% 37%	3907
	11th to 20th	Night	12% 2 3 21% 41% 21%	3897
	21st to end	Night	22% 3 5% 19% 34% 17%	4274
November	1st to 10th	Night	28% 4 7% 22% 23% 16%	2665
	11th to 20th	Night	29% 5% 7% 21% 27% 12%	2730
	21st to end	Night	30% 3 5% 21% 25% 16%	2788
December	1st to 10th	Night	25% 2 6% 20% 24% 23%	4700
	11th to 20th	Night	47% 4 7% 12% 21% 8%	5274
	21st to end	Night	48% 5% 9% 16% 14% 8%	6952

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	35% 19% 23% 15% 8% 1	200
	11th to 20th	Day	24% 16% 25% 20% 12% 3	300
	21st to end	Day	23% 16% 25% 21% 13% 3	440
February	1st to 10th	Day	30% 18% 24% 17% 9% 3	400
	11th to 20th	Day	23% 22% 31% 16% 7% 1	493
	21st to end	Day	24% 20% 34% 16% 5% 1	414
March	1st to 10th	Day	32% 25% 24% 13% 5% 1	500
	11th to 20th	Day	30% 22% 22% 15% 9% 1	500
	21st to end	Day	30% 22% 27% 16% 5%	550
April	1st to 10th	Day	22% 23% 31% 17% 7% 1	500
	11th to 20th	Day	24% 22% 26% 20% 6% 2	492
	21st to end	Day	15% 19% 30% 22% 10% 4	500
May	1st to 10th	Day	17% 23% 30% 19% 8% 3	503
	11th to 20th	Day	19% 19% 28% 20% 12% 3	528
	21st to end	Day	16% 16% 27% 22% 15% 4	573
June	1st to 10th	Day	9% 16% 35% 22% 12% 6%	530
	11th to 20th	Day	8% 23% 36% 21% 9% 4	530
	21st to end	Day	3 17% 38% 25% 11% 6%	530
July	1st to 10th	Day	3 10% 50% 20% 12% 5%	526
	11th to 20th	Day	2 10% 44% 28% 11% 5%	524
	21st to end	Day	3 8% 44% 26% 11% 7%	575
August	1st to 10th	Day	4 14% 43% 23% 12% 4	527
	11th to 20th	Day	3 14% 38% 29% 11% 5%	517
	21st to end	Day	3 9% 44% 28% 13% 3	583
September	1st to 10th	Day	4 13% 43% 25% 12% 2	530
	11th to 20th	Day	8% 17% 36% 28% 9% 2	530
	21st to end	Day	8% 16% 36% 32% 7% 1	530
October	1st to 10th	Day	10% 18% 28% 32% 10% 2	530
	11th to 20th	Day	11% 14% 31% 29% 12% 3	530
	21st to end	Day	12% 17% 29% 27% 11% 4	571
November	1st to 10th	Day	18% 14% 22% 25% 15% 5%	330
	11th to 20th	Day	19% 13% 27% 24% 10% 6%	330
	21st to end	Day	18% 15% 27% 23% 13% 3	297
December	1st to 10th	Day	18% 14% 24% 20% 17% 7%	220
	11th to 20th	Day	18% 19% 25% 21% 14% 4	214
	21st to end	Day	27% 13% 27% 20% 11% 2	220
January	1st to 10th	Night	22% 12% 24% 22% 14% 6%	800
	11th to 20th	Night	18% 13% 27% 29% 10% 3	800
	21st to end	Night	20% 12% 26% 23% 15% 4	880
February	1st to 10th	Night	22% 12% 23% 27% 13% 3	800
	11th to 20th	Night	20% 12% 23% 27% 13% 4	784
	21st to end	Night	21% 10% 28% 29% 10% 2	660
March	1st to 10th	Night	24% 12% 25% 25% 11% 2	800
	11th to 20th	Night	21% 11% 24% 24% 18% 3	800
	21st to end	Night	20% 11% 28% 28% 11% 1	880
April	1st to 10th	Night	17% 9% 25% 34% 14% 2	800
	11th to 20th	Night	14% 12% 26% 31% 14% 3	791
	21st to end	Night	12% 9% 24% 33% 18% 5%	800
May	1st to 10th	Night	10% 10% 25% 32% 19% 4	730
	11th to 20th	Night	7% 8% 21% 38% 23% 3	439
	21st to end	Night	9% 5% 19% 37% 26% 4	433
June	1st to 10th	Night	7% 4 19% 41% 26% 4	400
	11th to 20th	Night	2 5% 22% 43% 27% 3	400
	21st to end	Night	3 4 17% 45% 29% 3	400
July	1st to 10th	Night	1 14% 44% 39% 3	390
	11th to 20th	Night	2 2 13% 46% 33% 4	388
	21st to end	Night	3 1 11% 34% 41% 9%	570
August	1st to 10th	Night	4 1 13% 46% 31% 5%	619
	11th to 20th	Night	2 1 16% 46% 30% 5%	792
	21st to end	Night	3 1 11% 49% 33% 3	880
September	1st to 10th	Night	2 2 15% 46% 30% 4	800
	11th to 20th	Night	4 4 17% 39% 29% 8%	800
	21st to end	Night	4 4 22% 38% 24% 7%	800
October	1st to 10th	Night	8% 8% 19% 40% 20% 6%	800
	11th to 20th	Night	9% 8% 20% 36% 23% 5%	800
	21st to end	Night	8% 9% 22% 32% 19% 9%	880
November	1st to 10th	Night	13% 8% 18% 36% 20% 5%	820
	11th to 20th	Night	14% 10% 26% 31% 15% 4	840
	21st to end	Night	15% 12% 27% 28% 14% 4	840
December	1st to 10th	Night	19% 10% 25% 31% 11% 3	840
	11th to 20th	Night	23% 11% 23% 29% 12% 2	828
	21st to end	Night	25% 14% 24% 23% 11% 2	880

Page generated at 2025-12-14 22:13:51. Version ac07

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