Boyne Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Boyne Falls 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	14% 12% 5% 11% 5% 4 4 3 5% 6% 30%	108162
	Night	14% 14% 6% 13% 6% 5% 4 3 4 5% 26%	110985
Transparency	Day	54% 6% 10% 19% 10% 1	111703
	Night	59% 5% 10% 16% 8% 1	115607
Seeing	Day	20% 16% 30% 21% 9% 3	15991
	Night	21% 14% 30% 26% 9% 1	25810

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	8% 20% 11% 31% 6% 5% 4 2 3 3 8%	3617
	11th to 20th	Day	11% 17% 7% 26% 14% 10% 4 2 2 1 4	3589
	21st to end	Day	13% 19% 10% 21% 9% 5% 5% 2 4 3 9%	3982
February	1st to 10th	Day	8% 19% 8% 16% 14% 6% 4 3 4 5% 13%	1731
	11th to 20th	Day	12% 17% 7% 15% 10% 5% 5% 3 4 4 18%	1908
	21st to end	Day	12% 18% 7% 14% 7% 4 4 4 5% 5% 20%	1650
March	1st to 10th	Day	12% 14% 4 9% 6% 4 3 4 5% 6% 33%	3218
	11th to 20th	Day	8% 15% 7% 15% 5% 4 4 3 5% 6% 28%	3426
	21st to end	Day	16% 13% 7% 15% 6% 5% 4 3 4 5% 22%	3904
April	1st to 10th	Day	19% 16% 4 8% 4 4 4 3 5% 6% 27%	2280
	11th to 20th	Day	20% 14% 4 6% 3 4 2 2 5% 6% 33%	2378
	21st to end	Day	16% 12% 4 8% 4 4 4 4 6% 6% 31%	2470
May	1st to 10th	Day	16% 8% 2 6% 4 3 3 4 5% 7% 40%	4108
	11th to 20th	Day	12% 8% 2 6% 4 4 4 3 4 6% 46%	4197
	21st to end	Day	12% 7% 2 5% 4 4 4 4 6% 8% 43%	4859
June	1st to 10th	Day	15% 6% 2 6% 4 4 4 4 6% 8% 41%	2850
	11th to 20th	Day	14% 6% 2 6% 4 5% 5% 4 6% 8% 40%	2850
	21st to end	Day	16% 6% 2 6% 4 4 5% 4 6% 7% 40%	2850
July	1st to 10th	Day	19% 7% 2 6% 3 3 5% 3 5% 8% 38%	4441
	11th to 20th	Day	11% 5% 2 4 4 4 5% 4 6% 9% 48%	4440
	21st to end	Day	10% 5% 2 5% 4 4 5% 4 6% 9% 46%	4814
August	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 5% 7% 8% 39%	4212
	11th to 20th	Day	14% 6% 2 6% 4 4 4 3 5% 6% 45%	4044
	21st to end	Day	15% 7% 3 7% 4 4 4 3 5% 6% 44%	4411
September	1st to 10th	Day	16% 7% 2 5% 4 4 4 4 6% 7% 42%	2236
	11th to 20th	Day	14% 6% 2 5% 4 5% 4 4 5% 7% 45%	2090
	21st to end	Day	17% 8% 3 6% 4 4 4 3 6% 9% 36%	2090
October	1st to 10th	Day	19% 11% 3 8% 4 3 3 3 4 6% 35%	2080
	11th to 20th	Day	25% 17% 3 9% 5% 4 4 4 4 5% 19%	1810
	21st to end	Day	23% 19% 4 10% 5% 5% 5% 3 5% 5% 16%	1881
November	1st to 10th	Day	18% 21% 5% 9% 3 3 4 3 5% 6% 23%	1762
	11th to 20th	Day	13% 24% 7% 13% 6% 6% 3 3 4 5% 15%	1800
	21st to end	Day	17% 25% 11% 13% 5% 4 3 2 3 4 12%	1605
December	1st to 10th	Day	12% 31% 11% 19% 5% 4 3 3 3 3 6%	2280
	11th to 20th	Day	11% 25% 8% 22% 9% 5% 5% 3 3 3 6%	2621
	21st to end	Day	20% 23% 8% 17% 6% 4 3 2 3 4 9%	3678
January	1st to 10th	Night	10% 18% 9% 31% 7% 4 3 2 3 3 10%	6348
	11th to 20th	Night	11% 15% 7% 23% 15% 10% 4 2 3 2 6%	6316
	21st to end	Night	11% 19% 10% 20% 9% 7% 5% 2 3 3 10%	6996
February	1st to 10th	Night	9% 19% 7% 18% 12% 7% 4 3 3 3 14%	2667
	11th to 20th	Night	11% 15% 7% 17% 10% 5% 5% 3 4 5% 18%	2376
	21st to end	Night	13% 18% 5% 13% 6% 6% 4 3 4 5% 21%	1980
March	1st to 10th	Night	15% 11% 4 7% 4 4 4 3 4 6% 39%	3842
	11th to 20th	Night	8% 17% 6% 9% 5% 3 4 3 4 5% 34%	3548
	21st to end	Night	14% 13% 7% 10% 5% 4 4 3 6% 5% 27%	3754
April	1st to 10th	Night	19% 14% 3 8% 5% 4 4 3 6% 5% 28%	1900
	11th to 20th	Night	20% 11% 3 7% 5% 3 4 3 5% 6% 33%	1750
	21st to end	Night	16% 11% 3 9% 4 4 4 4 4 8% 34%	1710
May	1st to 10th	Night	15% 9% 3 6% 5% 5% 4 4 4 6% 39%	2833
	11th to 20th	Night	12% 9% 2 6% 5% 5% 4 4 5% 6% 41%	2698
	21st to end	Night	17% 7% 3 6% 4 4 3 2 5% 7% 42%	2725
June	1st to 10th	Night	15% 5% 2 5% 4 5% 5% 4 5% 7% 42%	1330
	11th to 20th	Night	11% 5% 2 7% 5% 4 4 4 7% 9% 42%	1330
	21st to end	Night	14% 7% 2 6% 4 4 5% 3 5% 6% 45%	1330
July	1st to 10th	Night	14% 7% 2 6% 3 4 4 4 6% 7% 42%	2522
	11th to 20th	Night	10% 4 2 6% 5% 4 4 3 5% 6% 51%	2530
	21st to end	Night	9% 6% 2 6% 5% 4 4 4 6% 8% 48%	2750
August	1st to 10th	Night	13% 6% 3 7% 4 5% 4 3 5% 7% 43%	2719
	11th to 20th	Night	16% 5% 2 5% 2 3 3 3 5% 8% 48%	2785
	21st to end	Night	11% 6% 2 5% 4 4 4 4 5% 6% 48%	3242
September	1st to 10th	Night	14% 5% 2 5% 4 3 3 4 5% 6% 49%	1924
	11th to 20th	Night	15% 6% 2 6% 4 3 3 3 5% 7% 46%	2090
	21st to end	Night	19% 8% 2 5% 4 4 4 3 5% 8% 38%	2090
October	1st to 10th	Night	19% 9% 2 6% 4 3 3 3 5% 6% 38%	2099
	11th to 20th	Night	22% 16% 3 8% 5% 5% 4 3 5% 5% 24%	2368
	21st to end	Night	26% 16% 4 7% 4 4 4 3 4 5% 22%	2717
November	1st to 10th	Night	17% 19% 5% 9% 4 4 4 2 4 7% 26%	2536
	11th to 20th	Night	15% 22% 7% 12% 6% 4 5% 3 4 5% 18%	2600
	21st to end	Night	17% 25% 9% 13% 4 4 3 3 4 5% 13%	2789
December	1st to 10th	Night	11% 27% 13% 18% 6% 5% 3 3 3 3 8%	4910
	11th to 20th	Night	12% 23% 8% 21% 8% 5% 4 2 3 3 10%	5586
	21st to end	Night	20% 22% 10% 16% 6% 4 4 3 3 4 10%	7295

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	83% 4 4 6% 2	3618
	11th to 20th	Day	89% 3 3 3 1	3620
	21st to end	Day	81% 4 8% 5% 2	3982
February	1st to 10th	Day	74% 6% 8% 9% 2	1731
	11th to 20th	Day	70% 6% 9% 9% 6%	1918
	21st to end	Day	66% 7% 8% 15% 4	1650
March	1st to 10th	Day	52% 6% 13% 18% 10% 1	3220
	11th to 20th	Day	57% 6% 12% 19% 5% 2	3426
	21st to end	Day	64% 6% 9% 13% 8% 1	3904
April	1st to 10th	Day	59% 5% 9% 17% 9% 1	2280
	11th to 20th	Day	53% 5% 10% 19% 13% 1	2378
	21st to end	Day	52% 6% 10% 15% 14% 3	2470
May	1st to 10th	Day	41% 7% 11% 21% 18% 2	4120
	11th to 20th	Day	37% 6% 10% 28% 17% 2	4201
	21st to end	Day	37% 6% 12% 22% 20% 2	4859
June	1st to 10th	Day	40% 7% 11% 27% 14% 2	2850
	11th to 20th	Day	41% 6% 12% 22% 17% 1	2850
	21st to end	Day	42% 6% 13% 25% 13% 1	2850
July	1st to 10th	Day	44% 6% 14% 23% 12% 1	4372
	11th to 20th	Day	31% 6% 12% 36% 14% 1	4365
	21st to end	Day	34% 7% 10% 30% 18% 1	4662
August	1st to 10th	Day	40% 7% 12% 27% 13% 1	4197
	11th to 20th	Day	39% 6% 12% 30% 12% 1	4083
	21st to end	Day	42% 6% 12% 30% 9% 1	4410
September	1st to 10th	Day	41% 6% 12% 25% 16% 1	2236
	11th to 20th	Day	38% 7% 14% 28% 12% 1	2090
	21st to end	Day	44% 6% 15% 24% 10%	2090
October	1st to 10th	Day	38% 4 8% 34% 16%	3457
	11th to 20th	Day	58% 4 9% 18% 11%	2987
	21st to end	Day	65% 6% 12% 15% 3	3081
November	1st to 10th	Day	61% 5% 10% 17% 6%	1762
	11th to 20th	Day	72% 5% 10% 9% 4	1800
	21st to end	Day	77% 4 10% 7% 1	1605
December	1st to 10th	Day	84% 5% 7% 4 1	2280
	11th to 20th	Day	84% 5% 6% 4 1	2621
	21st to end	Day	81% 4 5% 5% 4	3678
January	1st to 10th	Night	79% 5% 6% 7% 3	6348
	11th to 20th	Night	85% 4 6% 4 1	6360
	21st to end	Night	80% 5% 6% 7% 2	6996
February	1st to 10th	Night	75% 5% 6% 9% 3 1	2667
	11th to 20th	Night	69% 6% 9% 13% 3	2377
	21st to end	Night	66% 5% 10% 13% 6%	1980
March	1st to 10th	Night	47% 4 17% 21% 11% 1	3853
	11th to 20th	Night	51% 6% 12% 23% 8% 1	3549
	21st to end	Night	56% 8% 10% 18% 7% 1	3754
April	1st to 10th	Night	57% 6% 8% 18% 10% 1	1900
	11th to 20th	Night	52% 4 8% 21% 12% 2	1750
	21st to end	Night	50% 5% 10% 18% 14% 3	1710
May	1st to 10th	Night	44% 6% 11% 21% 15% 3	2840
	11th to 20th	Night	42% 6% 9% 25% 17% 1	2699
	21st to end	Night	42% 6% 14% 19% 14% 5%	2726
June	1st to 10th	Night	40% 6% 13% 25% 16% 1	1330
	11th to 20th	Night	38% 6% 13% 25% 14% 3	1330
	21st to end	Night	39% 7% 12% 25% 14% 2	1330
July	1st to 10th	Night	40% 5% 15% 23% 13% 3	2482
	11th to 20th	Night	33% 6% 13% 30% 18% 1	2482
	21st to end	Night	34% 7% 15% 24% 19%	2662
August	1st to 10th	Night	41% 6% 15% 25% 13% 1	2710
	11th to 20th	Night	36% 5% 15% 32% 12% 1	2812
	21st to end	Night	36% 5% 15% 28% 16% 1	3242
September	1st to 10th	Night	36% 7% 13% 25% 17% 2	1924
	11th to 20th	Night	37% 5% 16% 29% 12% 1	2090
	21st to end	Night	44% 8% 16% 23% 9%	2090
October	1st to 10th	Night	42% 5% 11% 29% 13% 1	3502
	11th to 20th	Night	51% 4 11% 21% 13%	3930
	21st to end	Night	60% 5% 13% 18% 4	4467
November	1st to 10th	Night	58% 7% 12% 16% 6% 1	2536
	11th to 20th	Night	70% 5% 9% 10% 5% 1	2600
	21st to end	Night	75% 6% 11% 7% 1	2789
December	1st to 10th	Night	82% 5% 7% 5% 1	4910
	11th to 20th	Night	79% 5% 8% 6% 2	5585
	21st to end	Night	79% 6% 7% 5% 3	7295

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	19% 21% 42% 14% 5%	300
	11th to 20th	Day	25% 23% 34% 14% 3	300
	21st to end	Day	24% 20% 36% 15% 4	330
February	1st to 10th	Day	20% 33% 33% 9% 4 1	300
	11th to 20th	Day	22% 31% 33% 11% 2	300
	21st to end	Day	26% 29% 37% 8% 1	249
March	1st to 10th	Day	23% 26% 38% 12% 2	300
	11th to 20th	Day	22% 20% 36% 16% 6%	425
	21st to end	Day	27% 15% 29% 21% 6% 1	506
April	1st to 10th	Day	27% 18% 32% 17% 5% 1	460
	11th to 20th	Day	31% 21% 26% 14% 7% 2	452
	21st to end	Day	19% 20% 31% 19% 9% 1	460
May	1st to 10th	Day	25% 20% 28% 16% 8% 3	463
	11th to 20th	Day	18% 15% 33% 22% 8% 4	551
	21st to end	Day	15% 14% 32% 27% 10% 2	734
June	1st to 10th	Day	15% 16% 33% 25% 9% 2	680
	11th to 20th	Day	18% 14% 32% 25% 9% 3	680
	21st to end	Day	20% 10% 32% 28% 9% 2	680
July	1st to 10th	Day	11% 10% 31% 30% 14% 4	671
	11th to 20th	Day	13% 10% 28% 30% 13% 5%	668
	21st to end	Day	11% 8% 31% 34% 13% 4	739
August	1st to 10th	Day	12% 8% 28% 27% 20% 6%	556
	11th to 20th	Day	13% 6% 22% 34% 16% 9%	479
	21st to end	Day	21% 8% 25% 27% 16% 4	539
September	1st to 10th	Day	20% 11% 25% 24% 16% 5%	490
	11th to 20th	Day	12% 11% 23% 30% 18% 6%	490
	21st to end	Day	19% 12% 23% 29% 13% 4	490
October	1st to 10th	Day	26% 17% 27% 18% 11% 2	490
	11th to 20th	Day	32% 19% 31% 16% 3 1	400
	21st to end	Day	34% 22% 30% 8% 4 1	330
November	1st to 10th	Day	31% 20% 30% 14% 5%	300
	11th to 20th	Day	26% 25% 34% 11% 3	300
	21st to end	Day	27% 28% 32% 11% 2	216
December	1st to 10th	Day	30% 21% 35% 10% 4 2	200
	11th to 20th	Day	25% 27% 38% 9% 2 1	200
	21st to end	Day	33% 30% 28% 6% 3 1	263
January	1st to 10th	Night	21% 20% 34% 20% 6%	1000
	11th to 20th	Night	21% 22% 32% 20% 5%	1000
	21st to end	Night	20% 16% 35% 23% 5%	1100
February	1st to 10th	Night	19% 21% 35% 21% 4	867
	11th to 20th	Night	20% 24% 29% 22% 5%	783
	21st to end	Night	24% 18% 34% 21% 3	660
March	1st to 10th	Night	19% 15% 36% 24% 6% 1	800
	11th to 20th	Night	18% 20% 35% 22% 5%	767
	21st to end	Night	21% 14% 29% 30% 7% 1	798
April	1st to 10th	Night	26% 12% 32% 23% 5% 1	570
	11th to 20th	Night	26% 11% 32% 23% 7%	563
	21st to end	Night	20% 11% 33% 28% 7% 1	570
May	1st to 10th	Night	17% 11% 32% 32% 8% 1	570
	11th to 20th	Night	18% 11% 32% 30% 9% 1	561
	21st to end	Night	15% 9% 26% 35% 14%	605
June	1st to 10th	Night	17% 7% 32% 33% 10% 1	380
	11th to 20th	Night	11% 8% 27% 40% 14%	380
	21st to end	Night	15% 7% 29% 36% 12% 1	380
July	1st to 10th	Night	13% 3 22% 45% 15% 1	547
	11th to 20th	Night	11% 5% 23% 36% 23% 2	552
	21st to end	Night	10% 4 25% 38% 21% 2	624
August	1st to 10th	Night	13% 2 23% 39% 23% 1	567
	11th to 20th	Night	15% 5% 16% 35% 26% 3	564
	21st to end	Night	17% 6% 22% 38% 16% 2	627
September	1st to 10th	Night	16% 5% 25% 32% 19% 3	594
	11th to 20th	Night	18% 6% 22% 35% 17% 3	760
	21st to end	Night	21% 10% 23% 30% 14% 3	760
October	1st to 10th	Night	23% 12% 25% 28% 11% 1	760
	11th to 20th	Night	31% 13% 29% 21% 5% 1	760
	21st to end	Night	34% 15% 28% 17% 5% 1	836
November	1st to 10th	Night	28% 15% 32% 20% 5%	780
	11th to 20th	Night	26% 21% 32% 18% 4	800
	21st to end	Night	30% 17% 34% 16% 2	825
December	1st to 10th	Night	24% 21% 34% 18% 3	1000
	11th to 20th	Night	23% 23% 34% 16% 3 1	1000
	21st to end	Night	28% 19% 32% 17% 3	1100

Page generated at 2025-03-09 08:08:42. Version ac07

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