Burk's Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burk's Falls clear sky chart from 2005-11-06 to 2025-08-05.

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% 12% 4 9% 5% 4 4 3 5% 6% 30%	126417
	Night	16% 14% 5% 10% 5% 4 4 3 4 5% 28%	121671
Transparency	Day	55% 4 10% 20% 9% 1	129978
	Night	58% 4 10% 18% 9% 1	126200
Seeing	Day	25% 15% 31% 19% 8% 2	15939
	Night	24% 13% 29% 25% 9% 1	24854

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% 18% 10% 16% 7% 5% 4 2 4 5% 18%	3158
	11th to 20th	Day	10% 22% 8% 19% 6% 6% 5% 4 4 4 13%	3639
	21st to end	Day	13% 22% 8% 16% 6% 5% 4 3 3 4 16%	4466
February	1st to 10th	Day	13% 20% 7% 16% 8% 4 4 3 4 4 19%	1800
	11th to 20th	Day	13% 18% 7% 13% 6% 4 4 3 4 5% 23%	1753
	21st to end	Day	15% 20% 6% 14% 7% 4 4 3 3 4 20%	1490
March	1st to 10th	Day	19% 16% 4 11% 5% 5% 3 3 3 5% 25%	4930
	11th to 20th	Day	12% 15% 6% 11% 5% 4 5% 4 6% 6% 25%	4980
	21st to end	Day	16% 18% 6% 8% 5% 4 3 2 3 5% 30%	5465
April	1st to 10th	Day	20% 16% 5% 7% 4 4 3 3 4 7% 27%	2379
	11th to 20th	Day	22% 13% 3 6% 4 4 3 3 4 5% 34%	2492
	21st to end	Day	21% 14% 3 8% 4 3 3 2 3 5% 33%	2600
May	1st to 10th	Day	19% 10% 3 8% 5% 4 5% 3 5% 7% 31%	6044
	11th to 20th	Day	14% 9% 3 8% 4 4 4 4 5% 7% 38%	6318
	21st to end	Day	22% 9% 3 7% 4 4 4 3 4 6% 34%	6949
June	1st to 10th	Day	20% 9% 3 7% 4 4 4 4 5% 8% 32%	2852
	11th to 20th	Day	15% 7% 3 7% 5% 5% 5% 3 5% 8% 37%	3000
	21st to end	Day	21% 9% 2 7% 5% 5% 4 4 6% 6% 32%	3000
July	1st to 10th	Day	17% 7% 3 6% 5% 4 5% 4 6% 8% 35%	6819
	11th to 20th	Day	14% 6% 2 6% 4 4 5% 3 5% 7% 44%	6590
	21st to end	Day	10% 5% 2 5% 4 4 4 3 6% 8% 48%	6745
August	1st to 10th	Day	13% 8% 3 7% 5% 5% 6% 5% 6% 8% 34%	4156
	11th to 20th	Day	18% 7% 3 6% 5% 5% 5% 4 6% 8% 34%	4044
	21st to end	Day	10% 5% 2 6% 5% 5% 4 5% 6% 8% 43%	4404
September	1st to 10th	Day	17% 7% 2 7% 5% 4 4 3 6% 7% 38%	2280
	11th to 20th	Day	16% 8% 2 6% 4 4 4 3 5% 6% 43%	2184
	21st to end	Day	23% 9% 2 7% 4 5% 4 3 4 6% 33%	2043
October	1st to 10th	Day	20% 10% 3 6% 4 5% 5% 3 5% 6% 33%	1900
	11th to 20th	Day	26% 14% 3 9% 5% 4 3 3 4 5% 23%	1900
	21st to end	Day	32% 14% 5% 8% 4 3 3 3 3 4 20%	2085
November	1st to 10th	Day	20% 16% 4 8% 5% 4 5% 3 4 6% 24%	1585
	11th to 20th	Day	19% 20% 6% 10% 5% 4 4 2 4 6% 21%	1600
	21st to end	Day	23% 21% 8% 11% 6% 4 4 2 4 4 13%	1600
December	1st to 10th	Day	17% 25% 8% 14% 7% 4 4 3 3 4 11%	2600
	11th to 20th	Day	18% 22% 6% 13% 6% 4 2 2 3 3 19%	2986
	21st to end	Day	20% 23% 7% 14% 5% 3 3 2 3 5% 14%	3581
January	1st to 10th	Night	12% 19% 9% 16% 8% 6% 4 3 4 4 16%	6808
	11th to 20th	Night	10% 19% 8% 21% 9% 6% 4 3 4 4 12%	6224
	21st to end	Night	12% 20% 11% 16% 7% 7% 4 3 3 3 15%	6490
February	1st to 10th	Night	12% 19% 6% 13% 8% 5% 5% 4 4 5% 19%	2600
	11th to 20th	Night	12% 17% 8% 14% 7% 4 4 3 4 5% 24%	2533
	21st to end	Night	12% 19% 6% 13% 8% 6% 4 2 5% 4 20%	2135
March	1st to 10th	Night	16% 16% 5% 10% 5% 4 4 3 4 5% 28%	4908
	11th to 20th	Night	10% 16% 7% 10% 5% 5% 5% 4 5% 7% 26%	4979
	21st to end	Night	21% 12% 6% 7% 6% 4 4 3 4 4 30%	5467
April	1st to 10th	Night	21% 16% 3 7% 4 4 4 3 5% 5% 29%	2020
	11th to 20th	Night	18% 12% 4 6% 4 4 5% 3 4 5% 35%	1875
	21st to end	Night	20% 11% 3 9% 6% 4 3 3 4 6% 31%	1800
May	1st to 10th	Night	17% 10% 3 7% 4 4 5% 4 6% 7% 34%	3897
	11th to 20th	Night	12% 6% 3 6% 4 4 4 4 6% 8% 42%	3575
	21st to end	Night	18% 11% 2 6% 4 4 4 3 5% 7% 36%	3926
June	1st to 10th	Night	15% 10% 3 7% 5% 5% 4 4 5% 6% 36%	1542
	11th to 20th	Night	16% 6% 1 5% 5% 3 5% 3 5% 8% 43%	1400
	21st to end	Night	16% 8% 3 6% 4 4 4 4 6% 7% 38%	1400
July	1st to 10th	Night	15% 7% 3 6% 4 4 4 4 6% 8% 40%	3160
	11th to 20th	Night	17% 6% 2 5% 3 3 3 3 5% 5% 47%	3377
	21st to end	Night	12% 7% 2 4 3 3 4 4 5% 8% 50%	4102
August	1st to 10th	Night	12% 6% 2 6% 4 4 4 3 6% 9% 45%	2861
	11th to 20th	Night	18% 7% 2 5% 3 3 4 4 5% 6% 43%	2785
	21st to end	Night	16% 5% 1 5% 3 3 3 3 4 7% 49%	3218
September	1st to 10th	Night	14% 5% 2 5% 4 4 4 4 6% 7% 45%	1900
	11th to 20th	Night	14% 6% 2 5% 3 4 4 3 5% 6% 48%	1993
	21st to end	Night	18% 8% 3 6% 3 4 4 3 5% 7% 40%	2137
October	1st to 10th	Night	19% 9% 3 7% 4 4 4 3 5% 5% 36%	2280
	11th to 20th	Night	24% 13% 3 8% 5% 4 5% 3 4 6% 25%	2280
	21st to end	Night	27% 18% 4 8% 4 4 3 3 3 4 23%	2511
November	1st to 10th	Night	23% 15% 3 6% 4 4 3 2 5% 6% 29%	2713
	11th to 20th	Night	19% 16% 4 9% 5% 5% 4 3 5% 6% 25%	2800
	21st to end	Night	23% 20% 6% 10% 6% 4 3 3 4 5% 15%	2800
December	1st to 10th	Night	18% 25% 7% 15% 6% 5% 4 3 4 4 10%	4580
	11th to 20th	Night	17% 23% 7% 14% 6% 4 3 2 3 4 16%	5208
	21st to end	Night	21% 22% 7% 15% 5% 3 3 2 3 3 15%	7387

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	71% 3 7% 14% 5%	3159
	11th to 20th	Day	76% 3 6% 9% 6% 1	3669
	21st to end	Day	74% 3 5% 10% 7% 1	4466
February	1st to 10th	Day	71% 3 6% 14% 6% 1	1800
	11th to 20th	Day	64% 4 9% 13% 8% 1	1762
	21st to end	Day	70% 2 8% 13% 7%	1490
March	1st to 10th	Day	64% 3 10% 8% 14% 2	4933
	11th to 20th	Day	58% 4 14% 15% 8% 2	4980
	21st to end	Day	59% 3 7% 19% 10% 2	5465
April	1st to 10th	Day	58% 3 10% 18% 9% 2	2379
	11th to 20th	Day	55% 3 6% 23% 12% 1	2492
	21st to end	Day	55% 3 8% 16% 14% 3	2600
May	1st to 10th	Day	52% 5% 8% 20% 9% 6%	6053
	11th to 20th	Day	45% 5% 9% 24% 16% 1	6322
	21st to end	Day	52% 4 10% 18% 13% 3	6949
June	1st to 10th	Day	52% 4 9% 22% 13%	2852
	11th to 20th	Day	45% 4 10% 26% 14% 1	3000
	21st to end	Day	51% 5% 13% 19% 10% 1	3000
July	1st to 10th	Day	45% 6% 14% 25% 9% 1	6746
	11th to 20th	Day	38% 5% 12% 35% 10%	6510
	21st to end	Day	34% 5% 13% 34% 14%	6551
August	1st to 10th	Day	45% 6% 13% 26% 9%	4143
	11th to 20th	Day	47% 5% 13% 26% 8%	4083
	21st to end	Day	38% 6% 12% 34% 10%	4404
September	1st to 10th	Day	44% 5% 12% 27% 11%	2280
	11th to 20th	Day	42% 4 14% 29% 11% 1	2184
	21st to end	Day	54% 4 9% 24% 8%	2043
October	1st to 10th	Day	51% 5% 11% 23% 9% 1	3160
	11th to 20th	Day	55% 6% 11% 22% 6%	3140
	21st to end	Day	67% 4 12% 14% 4	3411
November	1st to 10th	Day	61% 5% 12% 17% 5%	1585
	11th to 20th	Day	66% 5% 9% 13% 6% 1	1600
	21st to end	Day	75% 4 8% 9% 3 1	1600
December	1st to 10th	Day	77% 5% 9% 7% 1	2600
	11th to 20th	Day	71% 3 5% 13% 7%	2986
	21st to end	Day	75% 2 4 13% 6%	3581
January	1st to 10th	Night	74% 3 6% 13% 5%	6808
	11th to 20th	Night	76% 4 6% 7% 6%	6269
	21st to end	Night	75% 3 5% 8% 8% 1	6490
February	1st to 10th	Night	67% 4 9% 14% 6% 1	2600
	11th to 20th	Night	64% 3 8% 18% 6% 1	2535
	21st to end	Night	68% 3 9% 14% 6% 1	2135
March	1st to 10th	Night	58% 3 9% 13% 12% 4	4918
	11th to 20th	Night	57% 4 14% 16% 8% 1	4980
	21st to end	Night	58% 3 5% 20% 12% 2	5467
April	1st to 10th	Night	57% 4 8% 19% 11% 2	2020
	11th to 20th	Night	51% 4 7% 22% 15% 2	1875
	21st to end	Night	56% 5% 7% 15% 15% 2	1800
May	1st to 10th	Night	48% 5% 8% 23% 12% 4	3904
	11th to 20th	Night	39% 6% 11% 23% 18% 2	3576
	21st to end	Night	48% 4 10% 23% 14% 1	3927
June	1st to 10th	Night	48% 4 12% 21% 12% 3	1542
	11th to 20th	Night	39% 4 12% 27% 18%	1400
	21st to end	Night	44% 6% 15% 22% 12% 1	1400
July	1st to 10th	Night	41% 5% 14% 27% 10% 1	3125
	11th to 20th	Night	39% 4 12% 34% 11% 1	3335
	21st to end	Night	33% 5% 10% 38% 14% 1	3982
August	1st to 10th	Night	37% 6% 17% 24% 15% 2	2850
	11th to 20th	Night	40% 6% 18% 25% 9% 1	2812
	21st to end	Night	36% 4 13% 34% 12% 1	3218
September	1st to 10th	Night	36% 8% 14% 28% 13% 1	1900
	11th to 20th	Night	36% 5% 15% 31% 13%	1993
	21st to end	Night	44% 4 14% 27% 10%	2137
October	1st to 10th	Night	42% 5% 10% 28% 14%	3800
	11th to 20th	Night	53% 4 15% 20% 8%	3779
	21st to end	Night	61% 4 16% 13% 5%	4135
November	1st to 10th	Night	58% 4 13% 20% 6%	2713
	11th to 20th	Night	60% 5% 12% 16% 6% 1	2800
	21st to end	Night	72% 4 10% 10% 4	2800
December	1st to 10th	Night	79% 4 8% 6% 2	4580
	11th to 20th	Night	73% 3 6% 10% 7%	5208
	21st to end	Night	76% 3 6% 11% 5%	7387

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	23% 25% 34% 14% 4 1	200
	11th to 20th	Day	26% 20% 33% 16% 4	225
	21st to end	Day	28% 18% 32% 17% 5%	330
February	1st to 10th	Day	30% 30% 31% 6% 2 1	300
	11th to 20th	Day	28% 28% 33% 11% 1	300
	21st to end	Day	38% 22% 32% 8%	249
March	1st to 10th	Day	26% 22% 34% 14% 3	498
	11th to 20th	Day	24% 21% 37% 13% 4 1	500
	21st to end	Day	31% 19% 29% 15% 5% 1	550
April	1st to 10th	Day	30% 20% 30% 14% 5% 1	500
	11th to 20th	Day	37% 16% 23% 15% 6% 3	492
	21st to end	Day	33% 14% 33% 13% 6% 1	500
May	1st to 10th	Day	28% 14% 30% 18% 9% 2	503
	11th to 20th	Day	22% 15% 31% 19% 10% 3	527
	21st to end	Day	23% 17% 29% 19% 10% 2	573
June	1st to 10th	Day	23% 14% 32% 24% 6% 1	582
	11th to 20th	Day	19% 15% 33% 23% 8% 2	730
	21st to end	Day	25% 13% 34% 19% 8% 1	730
July	1st to 10th	Day	14% 11% 33% 29% 11% 1	721
	11th to 20th	Day	16% 12% 29% 28% 12% 3	619
	21st to end	Day	14% 11% 32% 28% 12% 3	576
August	1st to 10th	Day	17% 10% 27% 28% 12% 5%	502
	11th to 20th	Day	18% 7% 26% 24% 16% 9%	479
	21st to end	Day	18% 10% 30% 24% 14% 4	539
September	1st to 10th	Day	19% 11% 31% 22% 12% 6%	490
	11th to 20th	Day	18% 7% 24% 27% 17% 8%	490
	21st to end	Day	26% 12% 23% 22% 14% 3	490
October	1st to 10th	Day	26% 15% 26% 20% 10% 3	490
	11th to 20th	Day	31% 16% 33% 14% 4 2	490
	21st to end	Day	40% 16% 27% 15% 2	534
November	1st to 10th	Day	34% 20% 31% 14% 2	210
	11th to 20th	Day	31% 22% 36% 9% 4	200
	21st to end	Day	33% 20% 37% 8% 2 1	200
December	1st to 10th	Day	30% 17% 38% 14% 3	200
	11th to 20th	Day	37% 21% 30% 10% 2 1	200
	21st to end	Day	34% 22% 26% 14% 2 1	220
January	1st to 10th	Night	28% 17% 34% 17% 4 1	1000
	11th to 20th	Night	31% 15% 31% 19% 4	816
	21st to end	Night	21% 12% 35% 24% 7% 1	880
February	1st to 10th	Night	23% 19% 35% 20% 3	800
	11th to 20th	Night	22% 19% 33% 21% 5%	783
	21st to end	Night	24% 21% 30% 23% 3	660
March	1st to 10th	Night	22% 19% 35% 20% 4	800
	11th to 20th	Night	22% 18% 35% 20% 4 1	800
	21st to end	Night	24% 15% 29% 25% 7%	880
April	1st to 10th	Night	31% 12% 32% 20% 4	800
	11th to 20th	Night	25% 15% 27% 23% 10% 1	691
	21st to end	Night	25% 13% 28% 24% 10% 1	600
May	1st to 10th	Night	23% 8% 28% 31% 9% 1	535
	11th to 20th	Night	19% 9% 31% 32% 8%	394
	21st to end	Night	16% 9% 35% 33% 8%	433
June	1st to 10th	Night	17% 10% 32% 33% 9%	400
	11th to 20th	Night	18% 9% 24% 39% 10%	400
	21st to end	Night	20% 8% 26% 33% 13% 1	400
July	1st to 10th	Night	14% 4 25% 42% 15% 1	390
	11th to 20th	Night	15% 6% 25% 36% 18%	388
	21st to end	Night	12% 6% 24% 40% 17% 1	513
August	1st to 10th	Night	16% 4 17% 38% 22% 2	579
	11th to 20th	Night	15% 4 18% 39% 22% 2	564
	21st to end	Night	19% 5% 25% 31% 17% 3	682
September	1st to 10th	Night	16% 6% 26% 31% 18% 2	760
	11th to 20th	Night	16% 7% 25% 28% 21% 3	760
	21st to end	Night	22% 8% 23% 28% 16% 3	760
October	1st to 10th	Night	24% 11% 27% 26% 12% 1	760
	11th to 20th	Night	29% 12% 29% 21% 7% 1	760
	21st to end	Night	37% 14% 28% 17% 4	836
November	1st to 10th	Night	33% 12% 26% 21% 7% 1	780
	11th to 20th	Night	29% 18% 27% 21% 5%	800
	21st to end	Night	36% 13% 28% 19% 3 1	800
December	1st to 10th	Night	32% 17% 30% 16% 5%	800
	11th to 20th	Night	30% 18% 32% 15% 3 1	800
	21st to end	Night	34% 15% 29% 18% 3	1050

Page generated at 2025-08-02 01:32:24. Version ac07

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