Beaver Island
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beaver Island clear sky chart from 2005-11-06 to 2024-11-05.

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	14% 10% 4 9% 5% 4 4 3 5% 7% 35%	101257
	Night	15% 13% 5% 10% 6% 4 4 3 5% 6% 29%	97891
Transparency	Day	48% 7% 12% 22% 10% 1	104741
	Night	55% 7% 12% 17% 8% 1	102482
Seeing	Day	16% 5% 19% 31% 23% 6%	15707
	Night	21% 7% 24% 30% 16% 3	25324

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	14% 17% 12% 25% 7% 5% 4 2 3 3 7%	2527
	11th to 20th	Day	15% 16% 7% 20% 16% 8% 3 2 3 3 6%	2530
	21st to end	Day	14% 21% 9% 17% 8% 5% 4 3 3 5% 10%	2783
February	1st to 10th	Day	8% 14% 6% 13% 10% 6% 4 4 7% 6% 21%	1592
	11th to 20th	Day	12% 15% 5% 11% 9% 6% 5% 4 5% 7% 21%	1829
	21st to end	Day	12% 12% 5% 10% 8% 6% 6% 5% 5% 5% 25%	1570
March	1st to 10th	Day	12% 12% 4 9% 6% 4 4 3 5% 7% 36%	3118
	11th to 20th	Day	8% 11% 5% 15% 6% 5% 4 3 5% 6% 30%	3376
	21st to end	Day	15% 12% 6% 13% 7% 5% 5% 3 5% 5% 25%	3970
April	1st to 10th	Day	18% 11% 4 9% 4 4 5% 4 5% 7% 30%	2280
	11th to 20th	Day	18% 10% 4 7% 4 3 4 4 5% 6% 35%	2360
	21st to end	Day	15% 9% 3 10% 5% 5% 5% 4 5% 6% 35%	2470
May	1st to 10th	Day	14% 7% 2 6% 4 4 4 3 5% 7% 44%	4108
	11th to 20th	Day	11% 6% 3 7% 4 4 4 4 5% 7% 45%	4300
	21st to end	Day	11% 6% 2 5% 4 4 4 4 6% 9% 45%	4837
June	1st to 10th	Day	11% 7% 2 6% 5% 4 5% 4 5% 9% 43%	2839
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 4 6% 9% 42%	2850
	21st to end	Day	15% 6% 2 6% 4 4 4 4 6% 8% 42%	2835
July	1st to 10th	Day	15% 7% 3 5% 4 3 3 3 5% 7% 45%	4440
	11th to 20th	Day	6% 5% 2 4 3 3 4 4 6% 9% 53%	4440
	21st to end	Day	9% 5% 2 5% 3 3 3 4 6% 8% 53%	4814
August	1st to 10th	Day	7% 5% 2 7% 4 4 5% 4 6% 8% 46%	4303
	11th to 20th	Day	13% 5% 2 5% 4 3 4 3 5% 7% 51%	4044
	21st to end	Day	13% 6% 2 6% 4 4 4 3 4 6% 49%	4358
September	1st to 10th	Day	16% 6% 2 5% 3 3 4 4 6% 7% 44%	2264
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 6% 8% 44%	2090
	21st to end	Day	17% 7% 2 7% 5% 3 5% 3 5% 8% 37%	2090
October	1st to 10th	Day	19% 9% 3 7% 5% 3 4 3 5% 6% 36%	2090
	11th to 20th	Day	22% 16% 4 9% 5% 5% 5% 3 4 5% 22%	1776
	21st to end	Day	25% 16% 4 10% 5% 5% 4 3 5% 5% 18%	1881
November	1st to 10th	Day	19% 17% 5% 9% 4 4 4 3 5% 6% 24%	1708
	11th to 20th	Day	16% 21% 8% 13% 6% 5% 4 4 5% 4 15%	1710
	21st to end	Day	21% 22% 8% 12% 7% 5% 3 3 4 4 12%	1483
December	1st to 10th	Day	17% 24% 12% 16% 6% 5% 4 2 3 3 9%	1330
	11th to 20th	Day	18% 23% 7% 17% 8% 5% 3 2 4 3 9%	1671
	21st to end	Day	25% 23% 9% 15% 6% 4 3 2 2 3 8%	2591
January	1st to 10th	Night	13% 19% 8% 22% 7% 5% 4 3 4 4 12%	4428
	11th to 20th	Night	13% 17% 7% 21% 14% 6% 4 3 3 3 10%	4440
	21st to end	Night	15% 19% 8% 16% 8% 5% 4 3 4 4 13%	4884
February	1st to 10th	Night	9% 17% 6% 12% 9% 8% 6% 4 5% 5% 21%	2586
	11th to 20th	Night	11% 14% 5% 13% 9% 5% 5% 3 5% 6% 23%	2237
	21st to end	Night	13% 16% 4 11% 7% 5% 5% 4 4 5% 24%	1884
March	1st to 10th	Night	15% 11% 3 5% 4 3 3 3 4 7% 42%	3722
	11th to 20th	Night	9% 12% 5% 9% 6% 5% 4 4 5% 6% 36%	3581
	21st to end	Night	15% 11% 6% 10% 5% 4 4 4 6% 7% 29%	3690
April	1st to 10th	Night	19% 11% 3 8% 5% 5% 5% 3 5% 6% 29%	1900
	11th to 20th	Night	19% 9% 3 8% 4 4 4 3 5% 5% 35%	1768
	21st to end	Night	16% 8% 4 9% 5% 4 4 4 5% 5% 36%	1710
May	1st to 10th	Night	17% 7% 3 7% 4 4 4 3 4 6% 40%	2833
	11th to 20th	Night	12% 8% 3 8% 6% 5% 4 4 5% 6% 39%	2599
	21st to end	Night	18% 7% 2 6% 4 4 3 3 6% 7% 40%	2750
June	1st to 10th	Night	13% 5% 2 6% 5% 4 4 4 6% 9% 40%	1339
	11th to 20th	Night	12% 7% 3 7% 5% 5% 4 4 7% 7% 40%	1330
	21st to end	Night	14% 7% 3 6% 4 3 3 4 5% 8% 44%	1339
July	1st to 10th	Night	14% 7% 3 7% 4 3 5% 3 6% 7% 42%	2530
	11th to 20th	Night	7% 6% 3 5% 4 3 3 3 5% 7% 55%	2530
	21st to end	Night	9% 5% 2 6% 3 4 5% 3 5% 8% 50%	2750
August	1st to 10th	Night	10% 7% 2 6% 4 5% 4 4 5% 8% 43%	2630
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 7% 51%	2785
	21st to end	Night	11% 6% 2 5% 4 4 3 3 5% 7% 50%	3282
September	1st to 10th	Night	13% 6% 3 7% 5% 4 3 3 5% 7% 46%	1900
	11th to 20th	Night	16% 7% 2 5% 3 4 4 4 5% 7% 43%	2086
	21st to end	Night	18% 7% 3 6% 4 4 3 3 5% 7% 39%	2090
October	1st to 10th	Night	18% 9% 2 7% 4 4 4 3 5% 6% 37%	2090
	11th to 20th	Night	22% 13% 4 8% 5% 4 5% 4 5% 6% 25%	2402
	21st to end	Night	27% 14% 4 9% 5% 4 4 3 4 5% 21%	2717
November	1st to 10th	Night	18% 14% 5% 8% 5% 4 4 3 5% 6% 28%	2470
	11th to 20th	Night	18% 19% 6% 13% 6% 5% 5% 3 4 4 18%	2470
	21st to end	Night	19% 23% 9% 13% 6% 4 4 3 4 4 12%	2691
December	1st to 10th	Night	16% 26% 9% 16% 6% 4 4 2 4 4 10%	2850
	11th to 20th	Night	17% 19% 6% 18% 8% 5% 4 3 4 4 12%	3526
	21st to end	Night	24% 23% 10% 15% 5% 4 3 2 2 3 8%	5072

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% 6% 5% 4 1	2528
	11th to 20th	Day	84% 8% 4 3 1	2530
	21st to end	Day	78% 8% 9% 4 2	2783
February	1st to 10th	Day	60% 9% 12% 16% 3	1592
	11th to 20th	Day	60% 9% 12% 11% 7%	1839
	21st to end	Day	57% 8% 11% 17% 7%	1570
March	1st to 10th	Day	47% 5% 14% 21% 11% 1	3120
	11th to 20th	Day	51% 7% 16% 18% 7% 1	3376
	21st to end	Day	57% 7% 10% 17% 7% 1	3970
April	1st to 10th	Day	52% 7% 11% 21% 9% 1	2280
	11th to 20th	Day	48% 5% 10% 22% 13% 2	2360
	21st to end	Day	47% 6% 10% 18% 14% 3	2470
May	1st to 10th	Day	39% 7% 11% 24% 18% 2	4120
	11th to 20th	Day	39% 7% 10% 29% 15% 1	4304
	21st to end	Day	34% 8% 14% 23% 17% 4	4837
June	1st to 10th	Day	36% 8% 13% 26% 14% 2	2839
	11th to 20th	Day	37% 8% 13% 24% 16% 1	2850
	21st to end	Day	40% 7% 14% 25% 12% 2	2835
July	1st to 10th	Day	40% 5% 16% 24% 14% 1	4371
	11th to 20th	Day	26% 7% 15% 39% 12% 1	4365
	21st to end	Day	29% 7% 14% 31% 19%	4662
August	1st to 10th	Day	33% 8% 15% 31% 12% 1	4288
	11th to 20th	Day	33% 7% 13% 35% 11% 1	4083
	21st to end	Day	37% 7% 15% 31% 8% 1	4357
September	1st to 10th	Day	37% 8% 13% 29% 12% 1	2264
	11th to 20th	Day	37% 7% 18% 29% 8%	2090
	21st to end	Day	44% 7% 16% 23% 9%	2090
October	1st to 10th	Day	34% 5% 14% 31% 16%	3480
	11th to 20th	Day	54% 6% 12% 24% 4	2914
	21st to end	Day	59% 6% 16% 17% 3	3081
November	1st to 10th	Day	61% 6% 12% 16% 5%	1708
	11th to 20th	Day	72% 7% 11% 7% 3	1710
	21st to end	Day	77% 7% 10% 5% 1	1483
December	1st to 10th	Day	82% 5% 7% 5% 2	1330
	11th to 20th	Day	80% 8% 6% 4 2	1671
	21st to end	Day	83% 5% 6% 4 3	2591
January	1st to 10th	Night	76% 8% 8% 6% 1	4428
	11th to 20th	Night	80% 8% 8% 4 1	4440
	21st to end	Night	75% 9% 10% 4 2	4884
February	1st to 10th	Night	64% 8% 10% 13% 5%	2586
	11th to 20th	Night	61% 8% 12% 15% 4	2238
	21st to end	Night	60% 7% 11% 14% 7%	1884
March	1st to 10th	Night	44% 5% 19% 24% 8%	3733
	11th to 20th	Night	46% 6% 15% 25% 8% 1	3582
	21st to end	Night	52% 8% 13% 18% 8% 1	3690
April	1st to 10th	Night	55% 6% 11% 16% 12% 1	1900
	11th to 20th	Night	50% 4 11% 21% 11% 3	1768
	21st to end	Night	48% 6% 10% 19% 15% 3	1710
May	1st to 10th	Night	44% 7% 10% 23% 14% 2	2840
	11th to 20th	Night	45% 7% 9% 27% 12% 1	2600
	21st to end	Night	42% 8% 12% 18% 13% 7%	2751
June	1st to 10th	Night	40% 6% 14% 24% 15% 1	1339
	11th to 20th	Night	41% 7% 12% 22% 14% 4	1330
	21st to end	Night	38% 6% 14% 24% 15% 2	1339
July	1st to 10th	Night	41% 6% 14% 23% 14% 2	2490
	11th to 20th	Night	27% 7% 16% 32% 17% 1	2482
	21st to end	Night	33% 7% 12% 24% 23% 2	2662
August	1st to 10th	Night	37% 8% 14% 27% 13% 1	2621
	11th to 20th	Night	33% 6% 17% 30% 13% 1	2812
	21st to end	Night	33% 6% 15% 30% 15% 1	3282
September	1st to 10th	Night	39% 7% 13% 26% 15% 1	1900
	11th to 20th	Night	40% 6% 16% 27% 10% 1	2086
	21st to end	Night	45% 7% 15% 24% 9%	2090
October	1st to 10th	Night	41% 6% 13% 30% 10% 1	3480
	11th to 20th	Night	50% 7% 13% 21% 9%	3990
	21st to end	Night	58% 7% 13% 18% 4	4467
November	1st to 10th	Night	58% 7% 12% 16% 6%	2470
	11th to 20th	Night	71% 6% 11% 7% 5%	2470
	21st to end	Night	78% 6% 10% 6% 1	2691
December	1st to 10th	Night	80% 6% 8% 5% 1	2850
	11th to 20th	Night	76% 7% 10% 4 2	3525
	21st to end	Night	83% 6% 6% 4 1	5072

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% 10% 31% 29% 10% 1	270
	11th to 20th	Day	24% 10% 24% 30% 9% 2	270
	21st to end	Day	23% 4 28% 31% 14%	297
February	1st to 10th	Day	14% 7% 36% 33% 10% 1	270
	11th to 20th	Day	15% 7% 35% 28% 13% 1	270
	21st to end	Day	20% 8% 32% 35% 5%	225
March	1st to 10th	Day	16% 6% 25% 40% 13% 1	270
	11th to 20th	Day	13% 7% 27% 33% 16% 3	395
	21st to end	Day	22% 6% 21% 34% 14% 3	506
April	1st to 10th	Day	20% 7% 20% 39% 13% 2	460
	11th to 20th	Day	20% 8% 22% 29% 17% 4	452
	21st to end	Day	15% 4 22% 35% 19% 5%	460
May	1st to 10th	Day	19% 4 15% 37% 20% 5%	463
	11th to 20th	Day	16% 2 14% 35% 28% 5%	615
	21st to end	Day	14% 2 12% 33% 31% 8%	734
June	1st to 10th	Day	11% 2 13% 38% 30% 6%	680
	11th to 20th	Day	13% 1 13% 37% 28% 6%	680
	21st to end	Day	16% 3 11% 35% 28% 7%	680
July	1st to 10th	Day	9% 1 8% 36% 36% 10%	671
	11th to 20th	Day	9% 1 14% 30% 35% 10%	668
	21st to end	Day	9% 1 8% 33% 37% 11%	739
August	1st to 10th	Day	10% 3 9% 32% 35% 11%	608
	11th to 20th	Day	11% 4 9% 26% 39% 12%	479
	21st to end	Day	16% 4 12% 30% 29% 9%	539
September	1st to 10th	Day	19% 3 16% 29% 25% 8%	490
	11th to 20th	Day	12% 3 14% 29% 30% 10%	490
	21st to end	Day	17% 5% 20% 26% 27% 7%	490
October	1st to 10th	Day	19% 7% 27% 26% 17% 5%	490
	11th to 20th	Day	25% 11% 25% 27% 12% 1	356
	21st to end	Day	32% 9% 27% 23% 8% 2	330
November	1st to 10th	Day	20% 12% 29% 27% 12%	282
	11th to 20th	Day	21% 13% 36% 23% 6% 1	270
	21st to end	Day	25% 14% 39% 18% 4	205
December	1st to 10th	Day	28% 12% 30% 21% 7% 2	180
	11th to 20th	Day	26% 15% 33% 21% 4 1	180
	21st to end	Day	33% 16% 32% 13% 4 1	243
January	1st to 10th	Night	21% 9% 33% 27% 8% 1	950
	11th to 20th	Night	23% 9% 32% 26% 10% 1	950
	21st to end	Night	21% 7% 29% 32% 9% 1	1045
February	1st to 10th	Night	17% 5% 34% 33% 10% 1	876
	11th to 20th	Night	17% 6% 34% 31% 10% 1	743
	21st to end	Night	19% 7% 28% 36% 8% 1	628
March	1st to 10th	Night	17% 4 28% 36% 14% 1	760
	11th to 20th	Night	17% 5% 28% 37% 12% 1	760
	21st to end	Night	18% 4 23% 38% 14% 2	760
April	1st to 10th	Night	21% 4 28% 34% 9% 3	570
	11th to 20th	Night	22% 5% 20% 34% 16% 2	563
	21st to end	Night	18% 5% 21% 39% 16% 1	570
May	1st to 10th	Night	18% 4 17% 38% 21% 2	570
	11th to 20th	Night	18% 2 16% 42% 20% 2	561
	21st to end	Night	14% 2 13% 35% 31% 4	617
June	1st to 10th	Night	15% 1 13% 41% 27% 4	389
	11th to 20th	Night	13% 2 16% 38% 26% 5%	380
	21st to end	Night	16% 3 13% 30% 34% 4	389
July	1st to 10th	Night	13% 1 10% 36% 34% 6%	555
	11th to 20th	Night	10% 3 12% 33% 32% 10%	552
	21st to end	Night	10% 2 12% 39% 32% 5%	624
August	1st to 10th	Night	9% 2 11% 39% 32% 6%	567
	11th to 20th	Night	10% 2 12% 30% 36% 9%	564
	21st to end	Night	14% 3 12% 39% 28% 3	627
September	1st to 10th	Night	15% 4 18% 30% 26% 7%	570
	11th to 20th	Night	19% 4 16% 27% 26% 8%	756
	21st to end	Night	21% 6% 18% 26% 23% 7%	760
October	1st to 10th	Night	23% 6% 24% 26% 18% 3	760
	11th to 20th	Night	28% 11% 24% 27% 10% 1	760
	21st to end	Night	37% 8% 23% 24% 7% 1	836
November	1st to 10th	Night	26% 10% 28% 25% 10%	760
	11th to 20th	Night	28% 14% 31% 19% 7% 1	760
	21st to end	Night	29% 13% 34% 20% 5%	847
December	1st to 10th	Night	27% 14% 32% 20% 5% 1	950
	11th to 20th	Night	27% 13% 36% 16% 5% 2	950
	21st to end	Night	30% 12% 34% 20% 4	1045

Page generated at 2024-11-03 02:11:24. Version ac07

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