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 2025-03-12.

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%	108941
	Night	16% 12% 4 9% 5% 5% 4 3 5% 6% 31%	110059
Transparency	Day	51% 7% 12% 20% 10% 1	112493
	Night	52% 7% 12% 19% 10% 1	114671
Seeing	Day	22% 18% 31% 18% 8% 2	14784
	Night	22% 16% 32% 22% 8% 1	24096

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	12% 16% 5% 12% 8% 8% 6% 4 5% 5% 19%	3597
	11th to 20th	Day	11% 17% 8% 13% 7% 6% 5% 4 4 4 20%	3570
	21st to end	Day	12% 18% 7% 16% 7% 5% 4 3 4 4 19%	4259
February	1st to 10th	Day	13% 16% 5% 12% 7% 6% 4 4 4 5% 23%	1800
	11th to 20th	Day	11% 16% 5% 11% 7% 5% 5% 4 4 5% 28%	1753
	21st to end	Day	17% 15% 4 10% 7% 6% 5% 4 5% 4 25%	1621
March	1st to 10th	Day	18% 16% 5% 11% 5% 4 4 2 4 5% 27%	3303
	11th to 20th	Day	10% 16% 5% 11% 7% 5% 5% 3 4 5% 29%	3491
	21st to end	Day	11% 10% 4 9% 4 3 4 3 4 6% 42%	3969
April	1st to 10th	Day	21% 13% 3 6% 4 4 4 3 5% 5% 31%	2280
	11th to 20th	Day	22% 10% 3 6% 4 4 3 3 4 4 37%	2254
	21st to end	Day	21% 11% 4 7% 5% 4 4 3 4 4 32%	2406
May	1st to 10th	Day	20% 9% 3 7% 5% 5% 5% 3 6% 6% 33%	4426
	11th to 20th	Day	16% 9% 4 9% 5% 4 4 3 5% 8% 32%	4398
	21st to end	Day	14% 7% 2 7% 5% 5% 5% 4 6% 7% 39%	4837
June	1st to 10th	Day	20% 9% 4 7% 6% 4 5% 4 5% 7% 30%	2660
	11th to 20th	Day	15% 6% 2 7% 5% 5% 5% 4 6% 8% 37%	2660
	21st to end	Day	17% 7% 3 7% 6% 5% 5% 4 5% 7% 33%	2660
July	1st to 10th	Day	11% 7% 3 8% 6% 6% 5% 5% 7% 10% 34%	4440
	11th to 20th	Day	12% 5% 2 6% 4 5% 5% 5% 7% 9% 39%	4440
	21st to end	Day	10% 6% 2 6% 4 5% 5% 4 7% 8% 43%	4814
August	1st to 10th	Day	15% 8% 3 7% 5% 4 5% 4 5% 7% 35%	4245
	11th to 20th	Day	17% 6% 2 7% 4 5% 4 4 6% 8% 36%	4044
	21st to end	Day	13% 6% 2 6% 4 4 5% 4 7% 10% 39%	4183
September	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 3 6% 7% 40%	2280
	11th to 20th	Day	12% 6% 2 5% 4 4 5% 3 5% 7% 47%	2280
	21st to end	Day	17% 7% 2 7% 5% 5% 3 3 6% 7% 38%	2012
October	1st to 10th	Day	20% 8% 3 7% 4 5% 4 3 5% 6% 34%	1900
	11th to 20th	Day	20% 11% 3 8% 5% 4 4 3 5% 6% 29%	1900
	21st to end	Day	25% 11% 4 8% 5% 5% 5% 3 4 5% 26%	1981
November	1st to 10th	Day	14% 10% 3 8% 6% 5% 5% 4 5% 6% 34%	1732
	11th to 20th	Day	16% 13% 5% 9% 5% 5% 5% 3 5% 6% 28%	1600
	21st to end	Day	20% 16% 6% 10% 6% 6% 4 3 4 6% 20%	1600
December	1st to 10th	Day	21% 19% 5% 13% 7% 4 4 3 4 5% 14%	2600
	11th to 20th	Day	16% 18% 6% 12% 6% 4 3 3 4 4 24%	2986
	21st to end	Day	22% 18% 5% 14% 5% 3 3 2 3 4 21%	3960
January	1st to 10th	Night	14% 16% 8% 14% 7% 6% 5% 3 4 5% 19%	6349
	11th to 20th	Night	10% 15% 6% 14% 9% 6% 5% 4 5% 6% 20%	6315
	21st to end	Night	13% 18% 7% 13% 7% 7% 5% 3 4 5% 20%	6692
February	1st to 10th	Night	12% 17% 5% 12% 6% 5% 5% 4 6% 5% 23%	2600
	11th to 20th	Night	13% 13% 6% 11% 6% 6% 4 4 4 6% 28%	2533
	21st to end	Night	12% 13% 4 9% 6% 6% 5% 4 6% 5% 28%	2007
March	1st to 10th	Night	19% 14% 4 10% 6% 4 4 2 3 5% 30%	3755
	11th to 20th	Night	14% 16% 5% 10% 5% 4 5% 3 6% 6% 25%	3497
	21st to end	Night	14% 10% 3 7% 5% 4 4 3 5% 6% 39%	3663
April	1st to 10th	Night	20% 10% 3 8% 5% 4 3 3 4 5% 34%	1900
	11th to 20th	Night	19% 9% 3 7% 5% 5% 3 3 4 6% 36%	1875
	21st to end	Night	20% 10% 2 8% 4 4 4 4 4 6% 33%	1791
May	1st to 10th	Night	20% 10% 3 6% 4 5% 5% 3 5% 6% 32%	2514
	11th to 20th	Night	17% 8% 3 6% 4 5% 4 3 6% 7% 36%	2495
	21st to end	Night	13% 7% 3 6% 4 4 6% 4 5% 8% 41%	2738
June	1st to 10th	Night	15% 7% 3 7% 6% 4 5% 5% 6% 8% 35%	1520
	11th to 20th	Night	11% 7% 3 7% 5% 5% 4 4 6% 6% 43%	1520
	21st to end	Night	17% 8% 3 7% 3 5% 5% 3 6% 8% 36%	1520
July	1st to 10th	Night	10% 6% 3 8% 6% 6% 6% 5% 6% 7% 37%	2520
	11th to 20th	Night	12% 5% 2 7% 5% 5% 4 4 5% 8% 44%	2520
	21st to end	Night	10% 5% 2 6% 5% 5% 5% 4 6% 8% 44%	2739
August	1st to 10th	Night	11% 6% 2 7% 4 4 5% 4 6% 8% 42%	2682
	11th to 20th	Night	14% 6% 2 6% 5% 4 4 4 5% 7% 43%	2785
	21st to end	Night	12% 5% 2 6% 4 4 5% 4 6% 9% 43%	3440
September	1st to 10th	Night	12% 5% 3 6% 4 3 4 3 6% 6% 47%	1900
	11th to 20th	Night	14% 5% 2 4 3 4 4 3 5% 6% 51%	1900
	21st to end	Night	17% 7% 2 7% 3 3 3 4 6% 6% 43%	2166
October	1st to 10th	Night	18% 9% 3 6% 4 4 4 4 5% 6% 39%	2280
	11th to 20th	Night	19% 10% 3 9% 5% 5% 4 3 5% 6% 31%	2280
	21st to end	Night	21% 11% 4 8% 5% 4 4 3 5% 7% 28%	2617
November	1st to 10th	Night	16% 12% 3 8% 4 4 4 3 5% 5% 36%	2562
	11th to 20th	Night	16% 12% 3 8% 6% 5% 5% 4 5% 6% 30%	2800
	21st to end	Night	20% 16% 4 10% 5% 4 4 3 5% 6% 23%	2800
December	1st to 10th	Night	18% 17% 5% 11% 7% 6% 6% 4 5% 6% 16%	4580
	11th to 20th	Night	21% 15% 5% 11% 6% 5% 4 3 3 4 24%	5208
	21st to end	Night	25% 18% 4 12% 5% 4 3 2 3 3 20%	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	64% 10% 8% 11% 6% 1	3598
	11th to 20th	Day	65% 7% 10% 10% 8% 1	3600
	21st to end	Day	68% 5% 7% 12% 7% 1	4259
February	1st to 10th	Day	62% 7% 9% 15% 6% 1	1800
	11th to 20th	Day	58% 6% 11% 15% 9% 1	1762
	21st to end	Day	60% 8% 10% 11% 10% 1	1621
March	1st to 10th	Day	59% 5% 10% 14% 10% 1	3306
	11th to 20th	Day	54% 9% 12% 14% 9% 2	3491
	21st to end	Day	41% 6% 10% 23% 17% 4	3969
April	1st to 10th	Day	54% 5% 9% 17% 12% 3	2280
	11th to 20th	Day	50% 6% 7% 20% 16% 2	2254
	21st to end	Day	54% 6% 8% 14% 14% 3	2406
May	1st to 10th	Day	48% 8% 11% 19% 11% 2	4440
	11th to 20th	Day	46% 10% 13% 19% 10% 1	4402
	21st to end	Day	41% 9% 13% 20% 15% 2	4837
June	1st to 10th	Day	52% 8% 10% 17% 11% 1	2660
	11th to 20th	Day	42% 9% 11% 23% 12% 3	2660
	21st to end	Day	48% 8% 13% 19% 11% 1	2660
July	1st to 10th	Day	44% 6% 15% 24% 11% 1	4370
	11th to 20th	Day	37% 7% 16% 30% 10%	4365
	21st to end	Day	37% 7% 13% 31% 12%	4661
August	1st to 10th	Day	47% 7% 13% 23% 10%	4231
	11th to 20th	Day	43% 8% 14% 25% 8% 1	4083
	21st to end	Day	39% 6% 15% 30% 10% 1	4183
September	1st to 10th	Day	40% 9% 14% 27% 11%	2280
	11th to 20th	Day	35% 8% 14% 28% 15%	2280
	21st to end	Day	45% 7% 13% 25% 10%	2012
October	1st to 10th	Day	47% 5% 10% 30% 8%	3160
	11th to 20th	Day	46% 6% 14% 22% 12% 1	3140
	21st to end	Day	52% 5% 17% 20% 6%	3245
November	1st to 10th	Day	48% 8% 15% 21% 7% 1	1732
	11th to 20th	Day	56% 7% 11% 15% 9% 1	1600
	21st to end	Day	65% 9% 11% 8% 7% 1	1600
December	1st to 10th	Day	72% 6% 12% 7% 2	2600
	11th to 20th	Day	64% 5% 10% 14% 7%	2986
	21st to end	Day	69% 4 7% 14% 6%	3960
January	1st to 10th	Night	66% 8% 10% 11% 5%	6349
	11th to 20th	Night	63% 8% 11% 11% 6%	6360
	21st to end	Night	67% 6% 7% 8% 11% 1	6692
February	1st to 10th	Night	60% 6% 12% 16% 6% 1	2600
	11th to 20th	Night	56% 6% 12% 18% 8% 1	2535
	21st to end	Night	54% 7% 10% 18% 9% 1	2007
March	1st to 10th	Night	56% 6% 10% 19% 8% 1	3765
	11th to 20th	Night	54% 10% 15% 14% 7% 1	3498
	21st to end	Night	41% 8% 10% 22% 14% 4	3663
April	1st to 10th	Night	52% 6% 9% 18% 14% 2	1900
	11th to 20th	Night	50% 5% 8% 20% 15% 1	1875
	21st to end	Night	51% 6% 9% 16% 15% 3	1791
May	1st to 10th	Night	48% 10% 10% 20% 10% 2	2520
	11th to 20th	Night	43% 11% 15% 21% 10% 2	2496
	21st to end	Night	37% 10% 15% 19% 17% 2	2739
June	1st to 10th	Night	44% 10% 14% 20% 11% 1	1520
	11th to 20th	Night	39% 8% 12% 23% 17% 2	1520
	21st to end	Night	45% 11% 13% 18% 13% 1	1520
July	1st to 10th	Night	42% 8% 15% 20% 14% 1	2480
	11th to 20th	Night	38% 5% 13% 34% 10%	2472
	21st to end	Night	37% 8% 15% 26% 14%	2651
August	1st to 10th	Night	39% 8% 14% 26% 12% 1	2672
	11th to 20th	Night	39% 7% 16% 30% 8% 1	2812
	21st to end	Night	37% 7% 16% 27% 12% 1	3440
September	1st to 10th	Night	35% 7% 14% 28% 14% 1	1900
	11th to 20th	Night	33% 8% 14% 33% 12% 1	1900
	21st to end	Night	40% 7% 13% 29% 10% 1	2166
October	1st to 10th	Night	39% 6% 12% 30% 14%	3800
	11th to 20th	Night	44% 8% 16% 23% 9%	3779
	21st to end	Night	49% 6% 16% 21% 8%	4303
November	1st to 10th	Night	49% 7% 14% 20% 9% 1	2562
	11th to 20th	Night	53% 8% 12% 17% 9% 1	2800
	21st to end	Night	60% 8% 12% 15% 4	2800
December	1st to 10th	Night	67% 7% 14% 10% 2	4580
	11th to 20th	Night	64% 5% 8% 13% 10% 1	5208
	21st to end	Night	69% 5% 5% 11% 9%	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	22% 24% 39% 13% 4	200
	11th to 20th	Day	29% 23% 36% 11% 3	200
	21st to end	Day	22% 25% 37% 11% 4	285
February	1st to 10th	Day	30% 28% 30% 9% 3	300
	11th to 20th	Day	30% 29% 37% 4 1	300
	21st to end	Day	31% 28% 31% 10% 1	385
March	1st to 10th	Day	27% 22% 35% 13% 3	500
	11th to 20th	Day	27% 19% 35% 15% 3 1	464
	21st to end	Day	31% 24% 28% 13% 4	506
April	1st to 10th	Day	29% 23% 31% 12% 5%	460
	11th to 20th	Day	35% 22% 18% 16% 7% 2	452
	21st to end	Day	29% 22% 31% 10% 7% 1	460
May	1st to 10th	Day	25% 17% 32% 18% 5% 2	463
	11th to 20th	Day	18% 19% 34% 20% 7% 2	487
	21st to end	Day	19% 17% 32% 20% 9% 3	529
June	1st to 10th	Day	22% 14% 34% 20% 9% 1	490
	11th to 20th	Day	15% 18% 32% 24% 10% 1	490
	21st to end	Day	20% 15% 34% 19% 10% 1	490
July	1st to 10th	Day	11% 9% 32% 34% 11% 3	485
	11th to 20th	Day	13% 12% 33% 26% 12% 3	484
	21st to end	Day	15% 9% 35% 28% 10% 4	532
August	1st to 10th	Day	15% 8% 31% 28% 13% 4	486
	11th to 20th	Day	12% 9% 30% 29% 15% 5%	479
	21st to end	Day	14% 13% 29% 25% 12% 6%	539
September	1st to 10th	Day	15% 15% 30% 22% 11% 7%	490
	11th to 20th	Day	12% 12% 25% 24% 16% 11%	490
	21st to end	Day	19% 14% 29% 21% 12% 6%	490
October	1st to 10th	Day	24% 19% 26% 19% 9% 3	490
	11th to 20th	Day	25% 24% 30% 15% 5% 1	490
	21st to end	Day	30% 19% 30% 16% 4	482
November	1st to 10th	Day	25% 21% 31% 17% 6% 1	366
	11th to 20th	Day	27% 21% 33% 14% 4 2	200
	21st to end	Day	33% 25% 31% 8% 5%	200
December	1st to 10th	Day	30% 19% 39% 10% 3	200
	11th to 20th	Day	33% 30% 28% 6% 4 1	200
	21st to end	Day	30% 23% 30% 13% 4	220
January	1st to 10th	Night	25% 21% 36% 15% 3	800
	11th to 20th	Night	26% 21% 31% 17% 4 1	800
	21st to end	Night	20% 16% 38% 21% 5%	880
February	1st to 10th	Night	22% 21% 35% 19% 2	800
	11th to 20th	Night	21% 21% 42% 13% 3	783
	21st to end	Night	23% 23% 32% 20% 2	660
March	1st to 10th	Night	26% 20% 33% 19% 3	800
	11th to 20th	Night	24% 23% 32% 17% 4 1	767
	21st to end	Night	22% 18% 32% 21% 7%	836
April	1st to 10th	Night	27% 17% 32% 19% 4	760
	11th to 20th	Night	23% 22% 29% 19% 6%	751
	21st to end	Night	24% 17% 29% 22% 7% 1	651
May	1st to 10th	Night	20% 13% 31% 26% 10% 1	380
	11th to 20th	Night	20% 11% 34% 27% 7%	374
	21st to end	Night	11% 10% 40% 27% 11%	411
June	1st to 10th	Night	16% 12% 31% 33% 8%	380
	11th to 20th	Night	14% 10% 36% 29% 11% 1	380
	21st to end	Night	20% 9% 30% 28% 12%	380
July	1st to 10th	Night	7% 9% 33% 36% 14% 1	370
	11th to 20th	Night	11% 7% 29% 41% 11% 1	368
	21st to end	Night	10% 3 33% 43% 12% 1	416
August	1st to 10th	Night	11% 6% 27% 38% 18%	476
	11th to 20th	Night	12% 4 25% 36% 20% 3	564
	21st to end	Night	12% 8% 32% 30% 16% 2	813
September	1st to 10th	Night	14% 9% 32% 27% 16% 2	760
	11th to 20th	Night	15% 7% 23% 29% 21% 3	760
	21st to end	Night	18% 12% 24% 25% 19% 2	760
October	1st to 10th	Night	23% 13% 27% 22% 13% 2	760
	11th to 20th	Night	25% 16% 32% 19% 8% 1	760
	21st to end	Night	26% 19% 29% 21% 5%	836
November	1st to 10th	Night	25% 16% 31% 21% 6% 1	780
	11th to 20th	Night	24% 20% 33% 15% 8% 1	800
	21st to end	Night	31% 19% 28% 17% 5%	800
December	1st to 10th	Night	29% 19% 34% 16% 3	800
	11th to 20th	Night	28% 20% 31% 19% 2 1	800
	21st to end	Night	33% 16% 31% 16% 3	880

Page generated at 2025-03-09 08:08:41. Version ac07

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