Bayfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bayfield clear sky chart from 2005-11-06 to 2024-05-30.

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% 12% 4 9% 5% 4 4 3 5% 6% 31%	83730
	Night	17% 15% 5% 10% 5% 4 4 3 4 5% 27%	86146
Transparency	Day	53% 7% 12% 18% 9% 1	83442
	Night	59% 6% 11% 15% 8% 1	85969
Seeing	Day	19% 10% 27% 26% 14% 5%	14507
	Night	22% 10% 27% 28% 11% 1	23971

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	19% 25% 11% 17% 6% 3 2 1 2 3 10%	2404
	11th to 20th	Day	12% 25% 10% 23% 13% 4 2 1 2 2 6%	2658
	21st to end	Day	22% 22% 9% 17% 6% 4 3 2 2 3 8%	3124
February	1st to 10th	Day	15% 20% 5% 15% 9% 6% 4 3 4 5% 15%	1710
	11th to 20th	Day	13% 14% 9% 17% 8% 6% 4 3 4 5% 17%	1675
	21st to end	Day	15% 18% 6% 11% 6% 3 5% 4 4 5% 24%	1570
March	1st to 10th	Day	18% 14% 6% 9% 4 4 3 3 3 5% 29%	3304
	11th to 20th	Day	13% 16% 5% 11% 5% 4 4 3 5% 7% 29%	3480
	21st to end	Day	17% 11% 4 10% 5% 5% 4 3 5% 5% 31%	3815
April	1st to 10th	Day	16% 14% 5% 7% 4 4 3 4 5% 6% 31%	2170
	11th to 20th	Day	19% 10% 2 5% 4 4 4 4 5% 7% 36%	2442
	21st to end	Day	18% 10% 3 6% 4 4 4 3 5% 7% 36%	2470
May	1st to 10th	Day	15% 8% 3 7% 4 4 5% 4 7% 7% 36%	2470
	11th to 20th	Day	16% 8% 3 6% 4 4 3 3 6% 7% 40%	2431
	21st to end	Day	11% 7% 2 5% 4 4 4 4 6% 8% 43%	2847
June	1st to 10th	Day	10% 7% 2 7% 5% 5% 5% 5% 5% 8% 41%	2608
	11th to 20th	Day	10% 6% 1 5% 4 4 5% 5% 7% 9% 43%	2700
	21st to end	Day	13% 6% 2 4 4 4 4 4 7% 7% 43%	2700
July	1st to 10th	Day	7% 4 2 4 4 4 4 4 6% 8% 52%	2700
	11th to 20th	Day	10% 6% 2 5% 4 4 4 4 6% 9% 46%	2494
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 7% 8% 45%	2547
August	1st to 10th	Day	9% 5% 2 5% 4 5% 6% 3 8% 11% 42%	2327
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 4 7% 9% 42%	2303
	21st to end	Day	11% 6% 2 7% 4 4 4 3 5% 8% 45%	2570
September	1st to 10th	Day	12% 5% 2 7% 4 5% 4 4 7% 8% 41%	2088
	11th to 20th	Day	12% 5% 3 5% 4 4 5% 4 6% 8% 44%	1980
	21st to end	Day	18% 7% 2 6% 5% 4 5% 4 6% 8% 35%	1980
October	1st to 10th	Day	19% 8% 2 6% 6% 5% 4 4 5% 6% 35%	1854
	11th to 20th	Day	26% 15% 4 8% 5% 4 5% 3 5% 6% 20%	1800
	21st to end	Day	29% 15% 4 8% 5% 3 5% 4 4 5% 18%	1908
November	1st to 10th	Day	19% 16% 3 8% 5% 4 4 4 5% 6% 26%	1672
	11th to 20th	Day	19% 22% 4 10% 6% 3 4 4 5% 6% 18%	1566
	21st to end	Day	19% 28% 7% 10% 6% 4 3 3 3 4 12%	1520
December	1st to 10th	Day	18% 32% 9% 13% 6% 4 3 2 4 3 7%	1520
	11th to 20th	Day	20% 21% 10% 14% 6% 4 4 3 4 4 9%	1892
	21st to end	Day	28% 24% 7% 11% 4 4 3 3 3 4 8%	2431
January	1st to 10th	Night	18% 25% 11% 19% 6% 4 2 1 2 2 9%	4549
	11th to 20th	Night	16% 25% 9% 20% 12% 5% 2 2 2 2 6%	4304
	21st to end	Night	22% 21% 9% 16% 6% 4 3 2 3 3 10%	4532
February	1st to 10th	Night	17% 18% 5% 17% 10% 5% 4 3 3 3 15%	2470
	11th to 20th	Night	16% 16% 8% 14% 8% 5% 5% 3 4 5% 16%	2389
	21st to end	Night	16% 15% 6% 13% 6% 5% 5% 4 5% 4 22%	1884
March	1st to 10th	Night	15% 13% 4 8% 5% 4 4 3 4 6% 35%	3535
	11th to 20th	Night	12% 13% 6% 9% 5% 4 3 3 5% 7% 33%	3479
	21st to end	Night	16% 10% 4 10% 5% 4 4 3 5% 5% 34%	3817
April	1st to 10th	Night	21% 14% 3 6% 4 4 4 4 6% 5% 30%	2026
	11th to 20th	Night	20% 8% 3 7% 5% 4 4 3 5% 6% 36%	1687
	21st to end	Night	18% 11% 4 7% 5% 4 3 3 5% 7% 34%	1710
May	1st to 10th	Night	17% 8% 3 7% 4 4 5% 4 5% 9% 35%	1710
	11th to 20th	Night	15% 8% 3 7% 4 4 4 3 5% 7% 40%	1682
	21st to end	Night	10% 4 2 5% 3 4 4 5% 6% 7% 48%	1623
June	1st to 10th	Night	13% 6% 2 6% 5% 5% 4 4 5% 7% 43%	1348
	11th to 20th	Night	11% 6% 2 6% 4 4 3 5% 7% 9% 42%	1260
	21st to end	Night	12% 5% 2 6% 4 4 4 3 5% 9% 45%	1260
July	1st to 10th	Night	6% 5% 2 4 4 4 5% 4 6% 7% 53%	1260
	11th to 20th	Night	11% 5% 2 6% 3 3 5% 5% 6% 7% 48%	1460
	21st to end	Night	9% 4 3 7% 4 5% 5% 4 6% 9% 45%	1771
August	1st to 10th	Night	9% 4 2 6% 4 4 4 5% 7% 9% 45%	1611
	11th to 20th	Night	9% 5% 2 6% 3 5% 4 3 6% 9% 47%	1598
	21st to end	Night	12% 5% 2 5% 4 4 5% 4 6% 7% 46%	1782
September	1st to 10th	Night	12% 5% 2 6% 5% 4 5% 4 6% 7% 44%	1855
	11th to 20th	Night	14% 5% 2 5% 4 3 4 3 4 7% 49%	1980
	21st to end	Night	17% 7% 3 6% 5% 5% 5% 3 6% 6% 38%	1980
October	1st to 10th	Night	18% 10% 3 7% 4 4 4 2 5% 6% 37%	2106
	11th to 20th	Night	27% 10% 3 8% 6% 4 4 3 6% 5% 24%	2160
	21st to end	Night	30% 14% 4 9% 5% 4 4 3 4 5% 19%	2447
November	1st to 10th	Night	20% 16% 4 7% 5% 4 4 3 4 5% 29%	2406
	11th to 20th	Night	19% 22% 5% 11% 5% 5% 4 3 4 5% 18%	2612
	21st to end	Night	23% 25% 7% 10% 4 4 3 2 3 4 14%	2660
December	1st to 10th	Night	21% 32% 10% 11% 4 3 3 2 2 3 9%	2660
	11th to 20th	Night	17% 25% 10% 14% 5% 3 3 3 4 4 12%	3297
	21st to end	Night	27% 25% 7% 12% 5% 3 3 2 3 3 8%	5236

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	79% 6% 9% 5% 1	2405
	11th to 20th	Day	88% 3 5% 2 2	2658
	21st to end	Day	81% 7% 7% 4 1	3124
February	1st to 10th	Day	73% 7% 8% 10% 2	1710
	11th to 20th	Day	70% 6% 8% 12% 4	1684
	21st to end	Day	62% 7% 11% 14% 6% 1	1570
March	1st to 10th	Day	58% 6% 12% 19% 5% 1	3307
	11th to 20th	Day	54% 8% 13% 17% 6% 1	3480
	21st to end	Day	53% 7% 12% 17% 9% 2	3815
April	1st to 10th	Day	54% 6% 12% 18% 9%	2170
	11th to 20th	Day	46% 6% 12% 21% 13% 2	2442
	21st to end	Day	48% 7% 12% 19% 12% 2	2470
May	1st to 10th	Day	45% 7% 11% 23% 13% 1	2470
	11th to 20th	Day	44% 8% 11% 22% 13% 3	2435
	21st to end	Day	38% 7% 14% 22% 16% 2	2847
June	1st to 10th	Day	40% 8% 12% 25% 13% 2	2608
	11th to 20th	Day	36% 8% 12% 27% 16% 1	2700
	21st to end	Day	38% 8% 13% 26% 15%	2700
July	1st to 10th	Day	30% 8% 13% 27% 20% 2	2626
	11th to 20th	Day	33% 7% 15% 29% 14% 2	2418
	21st to end	Day	35% 8% 14% 27% 14% 2	2405
August	1st to 10th	Day	34% 10% 16% 29% 10% 1	2314
	11th to 20th	Day	36% 10% 16% 25% 11% 1	2303
	21st to end	Day	37% 7% 15% 27% 13% 1	2570
September	1st to 10th	Day	39% 8% 16% 23% 11% 2	2088
	11th to 20th	Day	36% 7% 14% 31% 11% 1	1980
	21st to end	Day	46% 8% 14% 23% 9%	1980
October	1st to 10th	Day	49% 8% 11% 20% 10% 1	1854
	11th to 20th	Day	63% 6% 11% 13% 5% 1	1800
	21st to end	Day	68% 7% 10% 11% 4	1908
November	1st to 10th	Day	57% 6% 11% 17% 7% 1	1672
	11th to 20th	Day	66% 6% 11% 10% 5% 1	1566
	21st to end	Day	77% 6% 8% 8% 1	1520
December	1st to 10th	Day	82% 6% 6% 5% 1	1520
	11th to 20th	Day	79% 6% 9% 6% 1	1892
	21st to end	Day	82% 4 11% 3	2431
January	1st to 10th	Night	80% 7% 7% 4 1	4549
	11th to 20th	Night	87% 4 6% 3 1	4304
	21st to end	Night	80% 5% 9% 5% 1	4532
February	1st to 10th	Night	75% 5% 7% 11% 2	2470
	11th to 20th	Night	70% 6% 10% 12% 3	2391
	21st to end	Night	62% 7% 12% 13% 6%	1884
March	1st to 10th	Night	51% 6% 13% 24% 6%	3545
	11th to 20th	Night	48% 8% 15% 19% 9% 1	3480
	21st to end	Night	50% 6% 12% 20% 11% 1	3817
April	1st to 10th	Night	53% 6% 9% 20% 12% 1	2026
	11th to 20th	Night	48% 5% 9% 18% 17% 2	1687
	21st to end	Night	51% 5% 9% 18% 15% 3	1710
May	1st to 10th	Night	46% 6% 10% 21% 15% 2	1710
	11th to 20th	Night	43% 6% 10% 21% 16% 4	1683
	21st to end	Night	32% 8% 14% 26% 16% 4	1624
June	1st to 10th	Night	40% 5% 11% 25% 16% 2	1348
	11th to 20th	Night	36% 7% 12% 25% 17% 4	1260
	21st to end	Night	36% 5% 14% 26% 17% 2	1260
July	1st to 10th	Night	28% 7% 11% 27% 23% 4	1225
	11th to 20th	Night	32% 8% 14% 27% 18% 2	1413
	21st to end	Night	34% 9% 15% 24% 16% 3	1672
August	1st to 10th	Night	33% 8% 14% 30% 14% 1	1600
	11th to 20th	Night	32% 7% 15% 28% 15% 2	1598
	21st to end	Night	36% 7% 13% 27% 15% 1	1782
September	1st to 10th	Night	37% 7% 14% 25% 15% 2	1855
	11th to 20th	Night	35% 5% 14% 28% 18% 1	1980
	21st to end	Night	44% 7% 14% 23% 12% 1	1980
October	1st to 10th	Night	47% 6% 11% 20% 14% 1	2106
	11th to 20th	Night	59% 6% 12% 17% 5% 1	2160
	21st to end	Night	67% 5% 9% 12% 6%	2447
November	1st to 10th	Night	55% 6% 12% 19% 8%	2406
	11th to 20th	Night	67% 5% 10% 12% 4 1	2612
	21st to end	Night	74% 5% 11% 8% 2	2660
December	1st to 10th	Night	83% 4 7% 5% 1	2660
	11th to 20th	Night	76% 5% 11% 6% 1	3297
	21st to end	Night	82% 5% 9% 4	5236

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	24% 17% 31% 17% 10% 1	236
	11th to 20th	Day	24% 16% 41% 13% 6%	270
	21st to end	Day	27% 13% 34% 21% 4 1	297
February	1st to 10th	Day	23% 21% 37% 15% 4	270
	11th to 20th	Day	20% 17% 45% 16% 2	270
	21st to end	Day	20% 28% 33% 16% 2	225
March	1st to 10th	Day	22% 15% 36% 22% 6% 1	379
	11th to 20th	Day	20% 15% 27% 29% 9%	460
	21st to end	Day	26% 12% 30% 24% 7% 1	506
April	1st to 10th	Day	19% 15% 37% 21% 8% 1	460
	11th to 20th	Day	27% 12% 27% 21% 10% 4	452
	21st to end	Day	22% 10% 33% 24% 10% 2	460
May	1st to 10th	Day	18% 10% 27% 30% 12% 2	463
	11th to 20th	Day	17% 8% 22% 30% 18% 5%	487
	21st to end	Day	14% 5% 21% 30% 21% 8%	521
June	1st to 10th	Day	11% 5% 30% 32% 16% 5%	538
	11th to 20th	Day	14% 5% 25% 35% 17% 5%	630
	21st to end	Day	17% 3 22% 38% 17% 3	630
July	1st to 10th	Day	9% 3 20% 32% 28% 9%	621
	11th to 20th	Day	12% 4 22% 32% 22% 7%	582
	21st to end	Day	8% 3 19% 41% 21% 7%	488
August	1st to 10th	Day	10% 3 18% 31% 25% 13%	446
	11th to 20th	Day	13% 2 13% 34% 25% 13%	439
	21st to end	Day	16% 4 18% 28% 25% 8%	495
September	1st to 10th	Day	14% 2 25% 27% 21% 11%	450
	11th to 20th	Day	9% 6% 19% 27% 26% 14%	450
	21st to end	Day	17% 9% 25% 24% 16% 9%	450
October	1st to 10th	Day	21% 8% 24% 26% 16% 6%	450
	11th to 20th	Day	30% 16% 25% 24% 5%	450
	21st to end	Day	33% 14% 31% 17% 4 1	423
November	1st to 10th	Day	23% 15% 31% 21% 9% 1	270
	11th to 20th	Day	26% 23% 29% 17% 4 1	201
	21st to end	Day	29% 17% 39% 12% 2	180
December	1st to 10th	Day	29% 22% 31% 13% 4	180
	11th to 20th	Day	29% 23% 30% 14% 4	180
	21st to end	Day	33% 19% 35% 11% 2	198
January	1st to 10th	Night	26% 17% 34% 17% 5% 1	950
	11th to 20th	Night	28% 16% 31% 20% 4	866
	21st to end	Night	22% 13% 35% 25% 5%	836
February	1st to 10th	Night	25% 14% 35% 23% 3	760
	11th to 20th	Night	23% 13% 33% 25% 6%	743
	21st to end	Night	24% 14% 37% 22% 4	628
March	1st to 10th	Night	20% 12% 35% 26% 8%	760
	11th to 20th	Night	19% 12% 37% 25% 7% 1	760
	21st to end	Night	22% 9% 30% 29% 9% 1	836
April	1st to 10th	Night	26% 13% 27% 29% 6%	753
	11th to 20th	Night	22% 10% 29% 27% 11% 1	563
	21st to end	Night	21% 9% 28% 31% 9% 1	570
May	1st to 10th	Night	21% 5% 26% 34% 13% 1	570
	11th to 20th	Night	18% 4 25% 37% 15% 1	561
	21st to end	Night	12% 3 23% 39% 20% 2	408
June	1st to 10th	Night	16% 3 21% 43% 16% 2	360
	11th to 20th	Night	12% 4 23% 44% 18%	360
	21st to end	Night	12% 3 18% 44% 22% 1	360
July	1st to 10th	Night	7% 1 13% 51% 25% 3	350
	11th to 20th	Night	12% 2 17% 39% 26% 4	509
	21st to end	Night	9% 2 16% 48% 24% 2	591
August	1st to 10th	Night	10% 3 11% 39% 34% 3	537
	11th to 20th	Night	10% 3 15% 37% 31% 5%	534
	21st to end	Night	13% 4 17% 35% 28% 3	594
September	1st to 10th	Night	14% 4 18% 37% 21% 6%	706
	11th to 20th	Night	13% 4 18% 33% 28% 5%	720
	21st to end	Night	19% 7% 21% 32% 16% 5%	720
October	1st to 10th	Night	22% 8% 25% 27% 17% 2	720
	11th to 20th	Night	30% 12% 24% 25% 8% 1	720
	21st to end	Night	35% 10% 29% 23% 3	792
November	1st to 10th	Night	27% 12% 27% 26% 9%	740
	11th to 20th	Night	29% 18% 31% 16% 5% 1	760
	21st to end	Night	33% 14% 29% 21% 4	760
December	1st to 10th	Night	34% 19% 29% 16% 3	760
	11th to 20th	Night	25% 21% 34% 16% 3 1	769
	21st to end	Night	33% 14% 35% 16% 2	1045

Page generated at 2024-05-27 00:31:44. Version ac07

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