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 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	14% 12% 4 10% 5% 4 4 3 5% 6% 31%	137264
	Night	14% 14% 5% 12% 6% 5% 4 3 4 5% 27%	135640
Transparency	Day	53% 5% 10% 20% 11% 1	140757
	Night	59% 5% 10% 17% 9% 1	140234
Seeing	Day	21% 17% 31% 21% 9% 2	17909
	Night	21% 14% 30% 26% 9% 1	27504

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% 21% 12% 29% 6% 4 3 2 3 2 7%	4691
	11th to 20th	Day	9% 19% 9% 25% 13% 11% 4 2 2 1 4	4679
	21st to end	Day	10% 15% 8% 20% 11% 8% 6% 3 3 4 11%	5156
February	1st to 10th	Day	8% 19% 8% 16% 15% 7% 4 4 4 5% 13%	1818
	11th to 20th	Day	12% 17% 7% 15% 9% 5% 5% 3 4 5% 18%	2006
	21st to end	Day	12% 19% 7% 14% 7% 4 4 4 5% 5% 19%	1730
March	1st to 10th	Day	13% 11% 4 12% 7% 4 4 4 6% 6% 31%	4578
	11th to 20th	Day	11% 14% 6% 12% 5% 5% 5% 4 5% 6% 26%	4996
	21st to end	Day	21% 12% 7% 15% 6% 4 4 3 4 4 20%	5720
April	1st to 10th	Day	19% 16% 4 8% 5% 4 4 3 5% 6% 27%	2520
	11th to 20th	Day	20% 14% 4 6% 3 4 2 3 5% 6% 33%	2632
	21st to end	Day	15% 13% 4 8% 4 4 4 5% 6% 6% 30%	2730
May	1st to 10th	Day	14% 9% 3 7% 4 3 4 4 5% 8% 41%	7642
	11th to 20th	Day	15% 9% 3 6% 5% 4 4 3 4 6% 41%	7840
	21st to end	Day	12% 8% 3 6% 4 3 4 3 5% 7% 45%	9097
June	1st to 10th	Day	15% 6% 2 6% 4 4 4 4 5% 8% 41%	3150
	11th to 20th	Day	14% 6% 2 6% 4 5% 5% 4 6% 8% 39%	3150
	21st to end	Day	16% 6% 2 6% 4 4 5% 4 6% 7% 40%	3150
July	1st to 10th	Day	17% 6% 2 5% 3 3 4 3 6% 9% 42%	6500
	11th to 20th	Day	12% 4 2 4 4 4 4 3 6% 9% 49%	6431
	21st to end	Day	10% 5% 2 5% 4 4 4 4 6% 10% 46%	6926
August	1st to 10th	Day	9% 6% 3 7% 4 5% 6% 5% 7% 8% 39%	4345
	11th to 20th	Day	15% 6% 2 6% 4 4 4 3 5% 6% 45%	4174
	21st to end	Day	14% 7% 3 7% 4 4 4 3 5% 6% 44%	4550
September	1st to 10th	Day	16% 7% 2 5% 4 4 4 4 6% 7% 41%	2353
	11th to 20th	Day	14% 6% 2 5% 5% 5% 4 4 6% 7% 45%	2200
	21st to end	Day	17% 8% 3 6% 4 4 4 3 6% 9% 37%	2200
October	1st to 10th	Day	19% 10% 3 8% 4 3 3 3 4 6% 36%	2189
	11th to 20th	Day	25% 17% 3 9% 5% 4 4 4 5% 5% 19%	1905
	21st to end	Day	22% 19% 4 10% 5% 5% 5% 3 5% 5% 18%	1980
November	1st to 10th	Day	18% 20% 5% 9% 4 4 4 3 5% 6% 24%	1852
	11th to 20th	Day	14% 24% 7% 13% 6% 6% 3 3 4 5% 15%	1890
	21st to end	Day	17% 26% 11% 14% 5% 4 3 2 3 4 12%	1684
December	1st to 10th	Day	11% 31% 11% 19% 6% 4 3 3 3 3 6%	2350
	11th to 20th	Day	11% 25% 8% 22% 9% 5% 5% 3 3 3 6%	2691
	21st to end	Day	20% 24% 8% 17% 6% 4 3 2 3 4 9%	3759
January	1st to 10th	Night	12% 18% 9% 31% 8% 4 3 2 3 3 9%	8233
	11th to 20th	Night	10% 18% 9% 23% 14% 11% 4 2 2 2 5%	8236
	21st to end	Night	8% 15% 9% 20% 12% 9% 6% 3 3 4 11%	9058
February	1st to 10th	Night	9% 19% 7% 17% 12% 8% 4 3 4 3 15%	2800
	11th to 20th	Night	11% 15% 7% 17% 10% 5% 5% 3 4 5% 19%	2498
	21st to end	Night	13% 19% 5% 13% 6% 6% 4 3 4 5% 21%	2076
March	1st to 10th	Night	15% 12% 4 9% 6% 4 4 3 4 6% 34%	5482
	11th to 20th	Night	11% 14% 5% 9% 5% 4 5% 4 5% 7% 31%	5169
	21st to end	Night	20% 14% 6% 10% 4 3 4 3 5% 5% 27%	5495
April	1st to 10th	Night	19% 14% 3 9% 5% 4 4 3 5% 5% 27%	2100
	11th to 20th	Night	21% 11% 3 7% 5% 4 4 3 5% 6% 33%	1936
	21st to end	Night	16% 11% 3 8% 4 4 4 3 4 8% 34%	1890
May	1st to 10th	Night	12% 8% 2 6% 5% 5% 5% 5% 5% 7% 39%	5257
	11th to 20th	Night	13% 9% 2 6% 4 4 4 4 6% 7% 41%	5016
	21st to end	Night	14% 8% 3 6% 4 3 3 3 5% 6% 46%	5095
June	1st to 10th	Night	15% 5% 2 5% 4 5% 4 4 6% 7% 42%	1470
	11th to 20th	Night	13% 5% 2 7% 5% 4 4 4 7% 9% 40%	1470
	21st to end	Night	14% 7% 2 6% 4 4 5% 3 5% 6% 44%	1470
July	1st to 10th	Night	13% 7% 2 7% 3 4 4 4 6% 8% 42%	3692
	11th to 20th	Night	11% 5% 2 5% 4 4 4 3 5% 6% 50%	3660
	21st to end	Night	8% 6% 2 5% 4 4 4 4 6% 8% 50%	3948
August	1st to 10th	Night	13% 6% 3 7% 4 5% 4 3 5% 7% 43%	2805
	11th to 20th	Night	16% 5% 2 5% 2 3 3 3 5% 8% 48%	2875
	21st to end	Night	11% 6% 2 5% 4 4 4 4 5% 6% 48%	3345
September	1st to 10th	Night	14% 5% 2 6% 4 3 3 4 5% 6% 48%	2026
	11th to 20th	Night	15% 6% 2 6% 4 3 3 3 5% 7% 46%	2200
	21st to end	Night	18% 9% 2 5% 4 4 4 3 5% 8% 38%	2200
October	1st to 10th	Night	19% 8% 2 6% 4 3 4 3 5% 6% 39%	2210
	11th to 20th	Night	22% 15% 3 8% 5% 5% 4 4 5% 5% 25%	2493
	21st to end	Night	26% 15% 4 7% 4 4 4 3 4 5% 23%	2860
November	1st to 10th	Night	17% 19% 5% 9% 4 4 3 3 4 7% 26%	2666
	11th to 20th	Night	14% 22% 7% 12% 6% 4 5% 3 4 5% 18%	2730
	21st to end	Night	17% 25% 9% 13% 4 4 3 3 4 5% 13%	2928
December	1st to 10th	Night	10% 27% 13% 19% 6% 5% 3 3 3 3 8%	5060
	11th to 20th	Night	12% 23% 8% 22% 8% 5% 4 2 3 4 10%	5736
	21st to end	Night	20% 21% 10% 16% 6% 4 4 3 3 4 10%	7455

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	85% 3 5% 5% 2	4692
	11th to 20th	Day	89% 3 3 3 1	4710
	21st to end	Day	79% 4 7% 7% 3	5156
February	1st to 10th	Day	74% 6% 8% 10% 2	1818
	11th to 20th	Day	69% 6% 8% 10% 7%	2016
	21st to end	Day	67% 6% 8% 15% 4	1730
March	1st to 10th	Day	53% 5% 15% 14% 10% 2	4580
	11th to 20th	Day	57% 5% 12% 17% 7% 1	4996
	21st to end	Day	67% 5% 8% 13% 7%	5720
April	1st to 10th	Day	59% 5% 9% 18% 9% 1	2520
	11th to 20th	Day	53% 4 10% 20% 12% 1	2632
	21st to end	Day	52% 6% 10% 15% 13% 3	2730
May	1st to 10th	Day	41% 6% 9% 24% 18% 2	7651
	11th to 20th	Day	44% 5% 7% 23% 19% 2	7844
	21st to end	Day	39% 5% 8% 24% 20% 4	9097
June	1st to 10th	Day	40% 6% 10% 27% 15% 2	3150
	11th to 20th	Day	42% 7% 12% 22% 16% 1	3150
	21st to end	Day	42% 6% 13% 25% 13% 1	3150
July	1st to 10th	Day	39% 5% 13% 28% 13% 1	6432
	11th to 20th	Day	32% 6% 12% 37% 13% 1	6356
	21st to end	Day	33% 6% 11% 34% 15% 1	6728
August	1st to 10th	Day	40% 7% 12% 28% 12% 1	4330
	11th to 20th	Day	39% 6% 12% 30% 12% 1	4213
	21st to end	Day	42% 6% 13% 30% 9% 1	4549
September	1st to 10th	Day	42% 6% 13% 24% 15% 1	2353
	11th to 20th	Day	37% 7% 14% 29% 12% 1	2200
	21st to end	Day	44% 6% 14% 24% 11%	2200
October	1st to 10th	Day	38% 4 9% 34% 16%	3566
	11th to 20th	Day	58% 4 8% 19% 11%	3082
	21st to end	Day	64% 6% 11% 15% 4	3180
November	1st to 10th	Day	60% 6% 10% 17% 6%	1852
	11th to 20th	Day	71% 5% 10% 9% 4	1890
	21st to end	Day	78% 4 10% 7% 2	1684
December	1st to 10th	Day	84% 5% 6% 4 1	2350
	11th to 20th	Day	84% 5% 6% 4 1	2691
	21st to end	Day	82% 4 5% 5% 4	3759
January	1st to 10th	Night	82% 4 6% 6% 2	8233
	11th to 20th	Night	87% 4 5% 3 1	8280
	21st to end	Night	78% 4 6% 8% 4	9058
February	1st to 10th	Night	74% 5% 7% 10% 3 1	2800
	11th to 20th	Night	68% 6% 9% 14% 3	2499
	21st to end	Night	66% 5% 10% 14% 5%	2076
March	1st to 10th	Night	52% 4 16% 18% 10% 1	5493
	11th to 20th	Night	52% 5% 16% 19% 7% 1	5170
	21st to end	Night	58% 6% 9% 16% 10% 1	5495
April	1st to 10th	Night	57% 6% 8% 18% 10% 1	2100
	11th to 20th	Night	53% 4 8% 21% 12% 2	1936
	21st to end	Night	50% 5% 10% 19% 13% 3	1890
May	1st to 10th	Night	41% 6% 10% 24% 16% 3	5264
	11th to 20th	Night	42% 5% 8% 26% 18% 1	5017
	21st to end	Night	40% 4 10% 23% 17% 6%	5096
June	1st to 10th	Night	39% 5% 12% 24% 18% 1	1470
	11th to 20th	Night	40% 6% 13% 25% 13% 2	1470
	21st to end	Night	40% 7% 12% 26% 13% 2	1470
July	1st to 10th	Night	39% 5% 14% 25% 14% 2	3652
	11th to 20th	Night	34% 5% 12% 30% 18% 1	3612
	21st to end	Night	31% 6% 16% 29% 17%	3832
August	1st to 10th	Night	40% 6% 15% 25% 13% 1	2796
	11th to 20th	Night	36% 5% 15% 32% 12% 1	2902
	21st to end	Night	36% 5% 15% 29% 15% 1	3345
September	1st to 10th	Night	36% 7% 15% 24% 17% 1	2026
	11th to 20th	Night	37% 6% 16% 28% 12% 1	2200
	21st to end	Night	44% 8% 15% 22% 10% 1	2200
October	1st to 10th	Night	41% 5% 11% 29% 13% 1	3613
	11th to 20th	Night	51% 4 11% 20% 13%	4055
	21st to end	Night	59% 5% 13% 19% 5%	4610
November	1st to 10th	Night	59% 7% 11% 16% 6% 1	2666
	11th to 20th	Night	69% 5% 10% 10% 5% 1	2730
	21st to end	Night	75% 6% 11% 7% 1	2928
December	1st to 10th	Night	82% 5% 7% 5% 1	5060
	11th to 20th	Night	79% 5% 8% 6% 2	5735
	21st to end	Night	79% 6% 7% 5% 3	7455

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% 21% 40% 13% 4	330
	11th to 20th	Day	26% 23% 33% 14% 3	330
	21st to end	Day	24% 21% 37% 15% 4	363
February	1st to 10th	Day	21% 32% 33% 9% 4 1	330
	11th to 20th	Day	23% 29% 34% 12% 2	330
	21st to end	Day	29% 28% 35% 7% 1	273
March	1st to 10th	Day	24% 26% 37% 12% 2	330
	11th to 20th	Day	26% 21% 34% 14% 5%	498
	21st to end	Day	31% 16% 28% 18% 6% 1	594
April	1st to 10th	Day	29% 20% 30% 15% 5% 1	540
	11th to 20th	Day	31% 20% 27% 13% 7% 2	532
	21st to end	Day	20% 20% 31% 19% 9% 1	540
May	1st to 10th	Day	25% 21% 29% 15% 8% 2	543
	11th to 20th	Day	21% 18% 31% 20% 7% 3	638
	21st to end	Day	17% 15% 32% 24% 9% 2	844
June	1st to 10th	Day	16% 16% 34% 24% 8% 2	780
	11th to 20th	Day	20% 15% 32% 23% 8% 2	780
	21st to end	Day	19% 11% 34% 26% 8% 2	780
July	1st to 10th	Day	12% 10% 33% 29% 13% 4	771
	11th to 20th	Day	13% 10% 31% 29% 12% 4	744
	21st to end	Day	11% 8% 32% 33% 12% 3	794
August	1st to 10th	Day	11% 8% 27% 29% 20% 6%	599
	11th to 20th	Day	14% 6% 23% 33% 16% 9%	519
	21st to end	Day	20% 8% 26% 26% 15% 4	583
September	1st to 10th	Day	20% 11% 26% 23% 15% 5%	530
	11th to 20th	Day	12% 10% 22% 29% 19% 7%	530
	21st to end	Day	18% 13% 23% 29% 12% 4	530
October	1st to 10th	Day	25% 16% 28% 19% 10% 2	530
	11th to 20th	Day	31% 19% 31% 16% 3	435
	21st to end	Day	32% 21% 32% 10% 4 1	363
November	1st to 10th	Day	32% 21% 29% 13% 5%	330
	11th to 20th	Day	28% 24% 33% 11% 3	330
	21st to end	Day	29% 28% 31% 10% 2	237
December	1st to 10th	Day	30% 22% 33% 10% 3 2	220
	11th to 20th	Day	27% 27% 36% 8% 1	220
	21st to end	Day	36% 28% 27% 6% 2 1	289
January	1st to 10th	Night	22% 20% 33% 19% 5%	1050
	11th to 20th	Night	21% 22% 32% 19% 5%	1050
	21st to end	Night	19% 17% 36% 23% 5%	1155
February	1st to 10th	Night	19% 21% 35% 21% 4	910
	11th to 20th	Night	20% 24% 29% 22% 5%	823
	21st to end	Night	25% 18% 33% 21% 3	692
March	1st to 10th	Night	19% 15% 36% 24% 6% 1	840
	11th to 20th	Night	21% 20% 34% 20% 5%	840
	21st to end	Night	21% 15% 29% 28% 6% 1	882
April	1st to 10th	Night	28% 12% 32% 22% 4 1	630
	11th to 20th	Night	27% 12% 30% 23% 8%	623
	21st to end	Night	20% 12% 33% 27% 7% 1	630
May	1st to 10th	Night	16% 11% 32% 32% 8%	630
	11th to 20th	Night	19% 11% 31% 30% 8% 1	621
	21st to end	Night	15% 10% 27% 35% 13%	669
June	1st to 10th	Night	16% 7% 33% 33% 10% 1	420
	11th to 20th	Night	13% 9% 28% 38% 13%	420
	21st to end	Night	15% 6% 31% 36% 11% 1	420
July	1st to 10th	Night	13% 4 22% 44% 16% 1	607
	11th to 20th	Night	11% 5% 23% 37% 22% 2	597
	21st to end	Night	9% 4 25% 40% 20% 2	657
August	1st to 10th	Night	12% 2 23% 39% 23% 1	597
	11th to 20th	Night	15% 5% 17% 35% 25% 3	594
	21st to end	Night	17% 6% 21% 38% 17% 2	660
September	1st to 10th	Night	16% 5% 25% 32% 19% 3	626
	11th to 20th	Night	17% 5% 21% 36% 18% 3	800
	21st to end	Night	20% 10% 23% 30% 14% 3	800
October	1st to 10th	Night	23% 11% 26% 28% 11% 1	800
	11th to 20th	Night	31% 13% 30% 21% 5% 1	800
	21st to end	Night	33% 15% 27% 19% 5% 1	880
November	1st to 10th	Night	29% 14% 31% 20% 5%	820
	11th to 20th	Night	26% 21% 31% 18% 4	840
	21st to end	Night	31% 17% 34% 16% 2	866
December	1st to 10th	Night	23% 21% 34% 18% 3	1050
	11th to 20th	Night	24% 24% 33% 15% 3 1	1050
	21st to end	Night	28% 20% 32% 17% 3	1155

Page generated at 2026-07-13 03:14:52. Version ac07

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