Black Creek Pond
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Black Creek Pond clear sky chart from 2005-11-06 to 2026-07-16.

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	15% 11% 4 9% 5% 5% 5% 4 5% 6% 32%	138582
	Night	15% 12% 4 9% 5% 5% 5% 3 5% 6% 31%	134096
Transparency	Day	51% 6% 11% 20% 11% 1	142088
	Night	52% 6% 11% 19% 10% 1	138679
Seeing	Day	23% 18% 31% 18% 7% 2	16552
	Night	22% 16% 31% 23% 8% 1	25683

By Month

Percentage Cloud Cover NE (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% 17% 5% 12% 8% 7% 6% 4 6% 6% 18%	4661
	11th to 20th	Day	11% 20% 9% 14% 7% 6% 5% 3 4 4 18%	4650
	21st to end	Day	9% 16% 7% 17% 8% 8% 6% 3 4 4 18%	5518
February	1st to 10th	Day	13% 15% 5% 12% 7% 6% 4 4 4 5% 23%	1890
	11th to 20th	Day	11% 15% 5% 11% 7% 5% 5% 4 4 5% 27%	1843
	21st to end	Day	17% 15% 4 10% 7% 6% 5% 4 5% 4 24%	1700
March	1st to 10th	Day	17% 14% 5% 11% 6% 4 4 3 5% 6% 26%	4704
	11th to 20th	Day	11% 13% 5% 10% 6% 5% 6% 4 5% 7% 29%	5090
	21st to end	Day	15% 13% 4 9% 5% 3 4 2 4 5% 37%	5815
April	1st to 10th	Day	20% 13% 4 7% 4 4 4 3 4 5% 31%	2520
	11th to 20th	Day	22% 11% 3 6% 5% 4 3 3 3 4 36%	2494
	21st to end	Day	21% 11% 3 7% 5% 4 4 3 4 4 32%	2659
May	1st to 10th	Day	21% 10% 3 8% 5% 5% 5% 4 6% 6% 29%	8237
	11th to 20th	Day	15% 8% 3 8% 5% 5% 5% 4 6% 7% 33%	8221
	21st to end	Day	19% 9% 2 7% 4 4 4 4 5% 6% 36%	9060
June	1st to 10th	Day	20% 8% 4 7% 6% 4 5% 3 5% 7% 31%	2940
	11th to 20th	Day	14% 6% 3 7% 5% 5% 5% 4 6% 8% 37%	2940
	21st to end	Day	16% 7% 3 7% 6% 5% 5% 4 5% 8% 33%	2940
July	1st to 10th	Day	14% 7% 3 8% 6% 5% 5% 4 6% 9% 34%	6500
	11th to 20th	Day	10% 5% 2 7% 4 5% 5% 4 7% 9% 43%	6430
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 6% 10% 45%	6926
August	1st to 10th	Day	15% 8% 3 7% 5% 4 5% 4 5% 7% 36%	4379
	11th to 20th	Day	17% 6% 2 7% 4 5% 4 4 6% 8% 36%	4174
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 7% 10% 39%	4315
September	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 3 6% 7% 41%	2400
	11th to 20th	Day	11% 6% 2 5% 4 4 4 3 5% 8% 48%	2400
	21st to end	Day	18% 6% 2 7% 5% 5% 3 3 6% 7% 38%	2117
October	1st to 10th	Day	20% 8% 3 7% 4 5% 4 3 5% 6% 36%	2000
	11th to 20th	Day	20% 11% 3 8% 6% 4 4 3 5% 7% 30%	2000
	21st to end	Day	25% 11% 3 8% 5% 5% 5% 3 4 5% 27%	2085
November	1st to 10th	Day	15% 11% 3 8% 6% 5% 5% 4 5% 6% 33%	1820
	11th to 20th	Day	16% 14% 5% 9% 5% 6% 5% 3 5% 6% 28%	1680
	21st to end	Day	19% 16% 6% 10% 6% 5% 4 3 4 6% 20%	1680
December	1st to 10th	Day	20% 19% 6% 13% 7% 4 4 3 4 5% 14%	2680
	11th to 20th	Day	16% 18% 6% 12% 6% 4 3 3 4 4 24%	3066
	21st to end	Day	22% 18% 5% 14% 5% 3 3 2 3 4 21%	4048
January	1st to 10th	Night	13% 15% 8% 15% 8% 6% 5% 3 4 5% 19%	8234
	11th to 20th	Night	11% 17% 6% 15% 9% 6% 5% 3 4 5% 18%	8235
	21st to end	Night	11% 16% 7% 12% 7% 7% 5% 4 5% 5% 22%	8658
February	1st to 10th	Night	12% 16% 5% 12% 7% 5% 5% 4 6% 5% 23%	2730
	11th to 20th	Night	12% 14% 6% 11% 6% 6% 5% 3 4 6% 28%	2663
	21st to end	Night	13% 14% 5% 9% 6% 6% 5% 4 6% 5% 27%	2104
March	1st to 10th	Night	20% 15% 4 10% 6% 4 4 2 3 4 28%	5354
	11th to 20th	Night	11% 13% 4 9% 6% 5% 6% 4 7% 8% 29%	5089
	21st to end	Night	17% 11% 3 9% 5% 4 4 3 5% 6% 33%	5359
April	1st to 10th	Night	20% 10% 4 9% 5% 3 3 3 5% 5% 33%	2100
	11th to 20th	Night	19% 10% 3 7% 5% 4 3 3 4 6% 36%	2075
	21st to end	Night	20% 10% 2 7% 4 4 4 4 4 7% 34%	1979
May	1st to 10th	Night	20% 10% 3 7% 5% 5% 5% 4 6% 7% 27%	4660
	11th to 20th	Night	13% 8% 3 7% 4 4 4 3 5% 7% 41%	4639
	21st to end	Night	19% 7% 2 7% 4 4 5% 4 6% 7% 35%	5114
June	1st to 10th	Night	15% 7% 2 7% 5% 4 5% 5% 6% 8% 36%	1680
	11th to 20th	Night	11% 7% 3 7% 5% 4 4 4 6% 6% 43%	1680
	21st to end	Night	16% 8% 3 6% 4 5% 5% 3 6% 8% 36%	1680
July	1st to 10th	Night	12% 6% 3 8% 5% 5% 6% 4 6% 8% 36%	3680
	11th to 20th	Night	12% 5% 2 6% 5% 4 4 4 5% 7% 46%	3640
	21st to end	Night	8% 5% 2 6% 4 5% 5% 3 6% 8% 48%	3926
August	1st to 10th	Night	11% 6% 2 7% 4 4 5% 4 6% 8% 43%	2767
	11th to 20th	Night	14% 6% 2 6% 5% 4 4 4 5% 7% 44%	2875
	21st to end	Night	12% 5% 2 6% 4 4 5% 3 6% 9% 43%	3549
September	1st to 10th	Night	11% 5% 3 5% 4 3 4 3 6% 6% 48%	2000
	11th to 20th	Night	13% 5% 2 4 3 4 4 3 5% 6% 52%	2000
	21st to end	Night	17% 7% 2 7% 3 4 3 3 6% 6% 43%	2280
October	1st to 10th	Night	17% 9% 3 6% 4 3 4 4 5% 6% 40%	2400
	11th to 20th	Night	18% 10% 3 8% 5% 5% 4 4 5% 7% 32%	2400
	21st to end	Night	21% 11% 3 8% 5% 4 4 3 5% 7% 29%	2755
November	1st to 10th	Night	16% 12% 3 8% 4 4 4 3 5% 5% 35%	2693
	11th to 20th	Night	16% 13% 4 8% 6% 5% 5% 4 5% 6% 30%	2940
	21st to end	Night	19% 16% 4 10% 5% 4 4 3 5% 6% 23%	2940
December	1st to 10th	Night	17% 18% 5% 11% 7% 6% 6% 4 5% 6% 16%	4720
	11th to 20th	Night	20% 15% 5% 11% 5% 5% 4 3 3 4 25%	5348
	21st to end	Night	24% 18% 4 12% 5% 4 3 2 3 4 20%	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	64% 8% 10% 12% 5%	4662
	11th to 20th	Day	68% 6% 8% 8% 9% 1	4680
	21st to end	Day	69% 5% 7% 11% 8% 1	5518
February	1st to 10th	Day	62% 7% 9% 16% 6% 1	1890
	11th to 20th	Day	58% 6% 11% 16% 8% 1	1852
	21st to end	Day	61% 7% 10% 11% 10% 1	1700
March	1st to 10th	Day	59% 5% 9% 12% 13% 2	4707
	11th to 20th	Day	52% 8% 15% 14% 10% 2	5090
	21st to end	Day	49% 4 7% 18% 18% 3	5815
April	1st to 10th	Day	55% 5% 9% 17% 12% 3	2520
	11th to 20th	Day	51% 6% 6% 19% 16% 2	2494
	21st to end	Day	53% 5% 9% 15% 14% 3	2659
May	1st to 10th	Day	52% 6% 9% 20% 11% 2	8249
	11th to 20th	Day	47% 7% 12% 21% 12% 1	8225
	21st to end	Day	47% 6% 11% 23% 13% 1	9061
June	1st to 10th	Day	51% 7% 10% 18% 13% 1	2940
	11th to 20th	Day	43% 8% 11% 23% 12% 2	2940
	21st to end	Day	47% 8% 13% 21% 11% 1	2940
July	1st to 10th	Day	45% 5% 14% 25% 10%	6430
	11th to 20th	Day	36% 6% 14% 29% 15%	6355
	21st to end	Day	34% 6% 14% 35% 11%	6728
August	1st to 10th	Day	46% 7% 14% 24% 10%	4365
	11th to 20th	Day	43% 8% 14% 26% 8% 1	4213
	21st to end	Day	39% 6% 15% 30% 10%	4315
September	1st to 10th	Day	39% 8% 14% 28% 11%	2400
	11th to 20th	Day	35% 7% 14% 29% 15%	2400
	21st to end	Day	46% 7% 13% 24% 11%	2117
October	1st to 10th	Day	46% 5% 10% 30% 8%	3260
	11th to 20th	Day	46% 6% 14% 22% 12% 1	3240
	21st to end	Day	51% 5% 17% 20% 6%	3349
November	1st to 10th	Day	49% 8% 14% 21% 7% 1	1820
	11th to 20th	Day	57% 6% 11% 15% 9% 1	1680
	21st to end	Day	66% 8% 10% 9% 7% 1	1680
December	1st to 10th	Day	72% 6% 12% 8% 2	2680
	11th to 20th	Day	64% 5% 10% 14% 7%	3066
	21st to end	Day	69% 4 7% 14% 6%	4048
January	1st to 10th	Night	66% 7% 10% 12% 5%	8234
	11th to 20th	Night	66% 7% 9% 11% 7%	8280
	21st to end	Night	63% 6% 6% 12% 11% 1	8658
February	1st to 10th	Night	60% 6% 11% 17% 6% 1	2730
	11th to 20th	Night	57% 5% 12% 18% 7% 1	2665
	21st to end	Night	55% 7% 10% 18% 9% 1	2104
March	1st to 10th	Night	59% 5% 7% 16% 10% 4	5364
	11th to 20th	Night	48% 8% 18% 15% 7% 2	5090
	21st to end	Night	50% 6% 9% 20% 12% 3	5359
April	1st to 10th	Night	53% 5% 9% 18% 13% 2	2100
	11th to 20th	Night	50% 4 8% 21% 15% 1	2075
	21st to end	Night	51% 6% 8% 17% 16% 2	1979
May	1st to 10th	Night	53% 8% 9% 20% 8% 3	4666
	11th to 20th	Night	40% 7% 14% 22% 14% 2	4640
	21st to end	Night	45% 7% 13% 19% 15% 1	5115
June	1st to 10th	Night	43% 9% 13% 21% 13% 1	1680
	11th to 20th	Night	39% 7% 12% 24% 16% 2	1680
	21st to end	Night	45% 10% 13% 19% 12% 1	1680
July	1st to 10th	Night	43% 6% 17% 19% 14% 1	3640
	11th to 20th	Night	37% 5% 13% 32% 13%	3592
	21st to end	Night	34% 6% 13% 33% 14%	3809
August	1st to 10th	Night	38% 8% 14% 26% 12% 1	2757
	11th to 20th	Night	39% 6% 16% 30% 9% 1	2902
	21st to end	Night	37% 7% 16% 28% 11% 1	3549
September	1st to 10th	Night	35% 7% 14% 29% 14% 1	2000
	11th to 20th	Night	32% 7% 13% 35% 12% 1	2000
	21st to end	Night	41% 7% 13% 28% 11% 1	2280
October	1st to 10th	Night	38% 6% 12% 30% 15%	3920
	11th to 20th	Night	43% 7% 16% 23% 10%	3899
	21st to end	Night	48% 6% 16% 21% 8%	4441
November	1st to 10th	Night	50% 6% 14% 20% 9% 1	2693
	11th to 20th	Night	53% 8% 12% 18% 8% 1	2940
	21st to end	Night	61% 8% 12% 15% 4	2940
December	1st to 10th	Night	67% 6% 14% 10% 2	4720
	11th to 20th	Night	63% 5% 8% 13% 10% 1	5348
	21st to end	Night	69% 5% 5% 11% 9%	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	22% 23% 39% 13% 4	220
	11th to 20th	Day	31% 22% 34% 10% 2	220
	21st to end	Day	22% 25% 37% 12% 4	314
February	1st to 10th	Day	29% 26% 32% 11% 3	330
	11th to 20th	Day	28% 28% 39% 4 1	330
	21st to end	Day	31% 28% 31% 10% 1	416
March	1st to 10th	Day	27% 24% 34% 12% 3	540
	11th to 20th	Day	31% 19% 33% 14% 2 1	540
	21st to end	Day	32% 24% 28% 12% 4	594
April	1st to 10th	Day	32% 23% 30% 11% 4	540
	11th to 20th	Day	36% 22% 19% 15% 7% 2	532
	21st to end	Day	30% 22% 31% 10% 6% 1	540
May	1st to 10th	Day	25% 21% 31% 16% 5% 2	543
	11th to 20th	Day	18% 20% 35% 19% 6% 2	567
	21st to end	Day	22% 17% 31% 19% 8% 2	617
June	1st to 10th	Day	22% 15% 35% 19% 8% 1	570
	11th to 20th	Day	16% 18% 34% 22% 9% 1	570
	21st to end	Day	19% 15% 35% 19% 10% 1	570
July	1st to 10th	Day	12% 10% 34% 32% 10% 2	565
	11th to 20th	Day	13% 13% 33% 26% 12% 3	544
	21st to end	Day	14% 11% 35% 27% 10% 4	576
August	1st to 10th	Day	14% 8% 31% 31% 13% 4	526
	11th to 20th	Day	13% 8% 30% 29% 15% 5%	519
	21st to end	Day	14% 12% 30% 25% 12% 6%	583
September	1st to 10th	Day	15% 15% 29% 22% 12% 7%	530
	11th to 20th	Day	12% 11% 25% 25% 16% 10%	530
	21st to end	Day	20% 13% 31% 20% 11% 5%	530
October	1st to 10th	Day	22% 19% 25% 21% 10% 3	530
	11th to 20th	Day	25% 24% 31% 15% 4 1	530
	21st to end	Day	30% 18% 31% 16% 4	520
November	1st to 10th	Day	27% 21% 31% 16% 5% 1	394
	11th to 20th	Day	28% 20% 33% 13% 5% 1	220
	21st to end	Day	33% 25% 31% 7% 4	220
December	1st to 10th	Day	28% 20% 41% 9% 3	220
	11th to 20th	Day	33% 29% 30% 5% 3	220
	21st to end	Day	31% 23% 30% 12% 3	242
January	1st to 10th	Night	25% 20% 36% 16% 3	840
	11th to 20th	Night	28% 21% 30% 17% 4 1	840
	21st to end	Night	20% 17% 37% 21% 4	924
February	1st to 10th	Night	21% 21% 35% 20% 2	840
	11th to 20th	Night	21% 21% 42% 14% 2	823
	21st to end	Night	23% 23% 32% 19% 2	692
March	1st to 10th	Night	27% 19% 33% 18% 3	840
	11th to 20th	Night	25% 22% 31% 17% 4	840
	21st to end	Night	24% 18% 32% 20% 6%	924
April	1st to 10th	Night	28% 18% 32% 19% 3	840
	11th to 20th	Night	25% 21% 29% 19% 6%	831
	21st to end	Night	25% 17% 29% 22% 6% 1	719
May	1st to 10th	Night	21% 13% 30% 26% 9% 1	420
	11th to 20th	Night	19% 12% 36% 26% 7%	414
	21st to end	Night	13% 10% 40% 27% 10%	455
June	1st to 10th	Night	15% 11% 31% 34% 7%	420
	11th to 20th	Night	13% 12% 36% 28% 10% 1	420
	21st to end	Night	19% 9% 30% 30% 12%	420
July	1st to 10th	Night	7% 10% 34% 36% 13% 1	410
	11th to 20th	Night	11% 7% 28% 42% 10% 1	398
	21st to end	Night	10% 3 33% 43% 11% 1	438
August	1st to 10th	Night	10% 5% 26% 39% 19%	501
	11th to 20th	Night	12% 4 25% 37% 20% 3	594
	21st to end	Night	12% 8% 32% 30% 16% 2	856
September	1st to 10th	Night	13% 9% 32% 28% 16% 2	800
	11th to 20th	Night	15% 7% 23% 30% 22% 3	800
	21st to end	Night	19% 12% 24% 25% 19% 2	800
October	1st to 10th	Night	22% 12% 27% 23% 13% 2	800
	11th to 20th	Night	24% 16% 33% 19% 8% 1	800
	21st to end	Night	26% 18% 29% 22% 5%	880
November	1st to 10th	Night	26% 17% 30% 21% 6%	820
	11th to 20th	Night	24% 20% 33% 15% 8% 1	840
	21st to end	Night	31% 19% 28% 17% 5%	840
December	1st to 10th	Night	28% 19% 33% 16% 3	840
	11th to 20th	Night	28% 20% 31% 18% 2	840
	21st to end	Night	33% 16% 31% 16% 3	924

Page generated at 2026-07-13 03:14:50. Version ac07

Copyright © 2026 Attilla Danko.