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 2024-11-11.

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% 11% 4 8% 5% 4 4 3 5% 7% 33%	101516
	Night	17% 14% 5% 10% 5% 4 4 3 4 5% 29%	97688
Transparency	Day	50% 7% 12% 19% 10% 1	105094
	Night	55% 6% 11% 17% 10% 1	102186
Seeing	Day	18% 10% 27% 26% 14% 5%	15196
	Night	22% 10% 27% 28% 12% 1	24498

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	16% 8% 3 7% 4 4 5% 4 6% 6% 37%	4108
	11th to 20th	Day	17% 8% 3 6% 4 4 4 3 5% 8% 37%	4081
	21st to end	Day	13% 6% 2 5% 4 4 4 3 6% 7% 47%	4833
June	1st to 10th	Day	11% 7% 2 7% 5% 5% 5% 5% 5% 8% 40%	2753
	11th to 20th	Day	9% 6% 1 5% 4 5% 5% 5% 7% 9% 43%	2850
	21st to end	Day	14% 6% 2 5% 4 4 4 4 7% 7% 43%	2850
July	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 7% 9% 42%	4760
	11th to 20th	Day	11% 5% 2 5% 4 4 4 3 6% 9% 50%	4386
	21st to end	Day	8% 5% 2 5% 4 5% 5% 4 7% 9% 47%	4466
August	1st to 10th	Day	12% 6% 2 6% 4 5% 5% 4 7% 9% 40%	4104
	11th to 20th	Day	10% 6% 2 7% 4 5% 5% 4 8% 10% 38%	4044
	21st to end	Day	9% 5% 2 7% 4 5% 4 3 6% 8% 45%	4514
September	1st to 10th	Day	12% 5% 2 7% 4 4 4 4 7% 8% 42%	2204
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 4 6% 8% 46%	2090
	21st to end	Day	18% 7% 2 6% 5% 4 5% 5% 6% 8% 34%	2090
October	1st to 10th	Day	18% 8% 2 6% 6% 5% 4 4 5% 6% 36%	1956
	11th to 20th	Day	25% 14% 4 7% 5% 4 5% 3 5% 6% 22%	1900
	21st to end	Day	28% 15% 4 8% 5% 3 5% 4 4 5% 18%	2014
November	1st to 10th	Day	19% 16% 3 8% 5% 4 4 4 4 6% 26%	1762
	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	18% 8% 3 6% 4 3 4 3 4 8% 39%	2833
	11th to 20th	Night	14% 9% 3 8% 5% 4 4 3 5% 7% 38%	2812
	21st to end	Night	12% 4 2 5% 3 4 4 4 5% 7% 50%	2739
June	1st to 10th	Night	14% 7% 2 7% 5% 5% 4 3 5% 7% 42%	1422
	11th to 20th	Night	11% 6% 2 7% 4 4 4 5% 7% 9% 41%	1330
	21st to end	Night	12% 5% 2 6% 4 4 5% 3 5% 9% 45%	1330
July	1st to 10th	Night	7% 6% 2 6% 5% 5% 4 5% 6% 8% 46%	2210
	11th to 20th	Night	11% 5% 2 5% 3 3 4 4 5% 6% 53%	2576
	21st to end	Night	7% 5% 2 7% 4 5% 5% 4 6% 9% 46%	3087
August	1st to 10th	Night	11% 6% 2 7% 4 4 4 4 5% 8% 44%	2825
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 6% 9% 44%	2785
	21st to end	Night	11% 5% 3 6% 4 4 4 4 5% 7% 47%	3124
September	1st to 10th	Night	12% 5% 2 6% 5% 4 5% 4 6% 6% 45%	1959
	11th to 20th	Night	13% 4 2 5% 4 3 4 3 4 7% 51%	2090
	21st to end	Night	18% 8% 3 6% 5% 5% 5% 3 6% 6% 38%	2090
October	1st to 10th	Night	17% 10% 3 7% 4 4 4 2 5% 6% 39%	2223
	11th to 20th	Night	26% 10% 3 8% 6% 4 4 2 6% 5% 25%	2280
	21st to end	Night	28% 13% 4 8% 5% 4 4 3 5% 5% 21%	2583
November	1st to 10th	Night	20% 16% 4 7% 5% 4 4 3 4 5% 29%	2536
	11th to 20th	Night	20% 22% 5% 11% 5% 5% 4 3 4 5% 18%	2619
	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	44% 8% 12% 20% 14% 2	4120
	11th to 20th	Day	45% 11% 14% 20% 8% 2	4085
	21st to end	Day	35% 8% 12% 20% 20% 6%	4833
June	1st to 10th	Day	41% 8% 12% 24% 13% 1	2753
	11th to 20th	Day	35% 8% 12% 26% 17% 1	2850
	21st to end	Day	39% 7% 13% 26% 15%	2850
July	1st to 10th	Day	38% 7% 15% 22% 16% 2	4686
	11th to 20th	Day	32% 6% 12% 35% 13% 1	4310
	21st to end	Day	32% 7% 17% 24% 18% 2	4324
August	1st to 10th	Day	39% 9% 12% 25% 15% 1	4091
	11th to 20th	Day	38% 10% 16% 26% 10%	4083
	21st to end	Day	36% 7% 13% 30% 13% 1	4514
September	1st to 10th	Day	39% 8% 16% 25% 11% 2	2204
	11th to 20th	Day	35% 7% 14% 30% 14% 1	2090
	21st to end	Day	46% 8% 14% 23% 9%	2090
October	1st to 10th	Day	43% 7% 12% 24% 13% 1	3242
	11th to 20th	Day	46% 6% 12% 23% 12%	3140
	21st to end	Day	57% 6% 15% 17% 5%	3303
November	1st to 10th	Day	58% 6% 11% 18% 7% 1	1762
	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	44% 7% 11% 19% 16% 4	2840
	11th to 20th	Night	44% 8% 12% 22% 12% 2	2813
	21st to end	Night	32% 8% 12% 23% 21% 5%	2740
June	1st to 10th	Night	41% 5% 10% 25% 16% 2	1422
	11th to 20th	Night	36% 7% 12% 25% 16% 4	1330
	21st to end	Night	37% 5% 13% 26% 17% 2	1330
July	1st to 10th	Night	34% 6% 13% 25% 17% 6%	2175
	11th to 20th	Night	31% 6% 12% 30% 20% 1	2529
	21st to end	Night	34% 8% 14% 23% 19% 2	2988
August	1st to 10th	Night	38% 6% 12% 27% 16% 1	2814
	11th to 20th	Night	38% 7% 14% 25% 15% 1	2812
	21st to end	Night	36% 6% 11% 33% 14% 1	3124
September	1st to 10th	Night	37% 7% 13% 25% 15% 2	1959
	11th to 20th	Night	33% 5% 13% 28% 20% 1	2090
	21st to end	Night	45% 7% 13% 22% 12%	2090
October	1st to 10th	Night	36% 5% 12% 25% 21% 1	3704
	11th to 20th	Night	49% 6% 15% 19% 11%	3779
	21st to end	Night	53% 5% 15% 20% 7%	4244
November	1st to 10th	Night	55% 6% 12% 19% 8%	2536
	11th to 20th	Night	67% 5% 10% 12% 4 1	2619
	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% 22% 8%	529
June	1st to 10th	Day	11% 5% 31% 31% 16% 5%	583
	11th to 20th	Day	14% 5% 27% 35% 16% 4	680
	21st to end	Day	18% 4 22% 37% 16% 3	680
July	1st to 10th	Day	9% 5% 21% 31% 26% 8%	671
	11th to 20th	Day	12% 4 23% 32% 22% 7%	630
	21st to end	Day	8% 3 20% 40% 22% 8%	532
August	1st to 10th	Day	10% 3 19% 31% 24% 12%	486
	11th to 20th	Day	13% 2 15% 34% 24% 13%	479
	21st to end	Day	15% 4 18% 29% 26% 7%	539
September	1st to 10th	Day	14% 3 25% 26% 21% 11%	490
	11th to 20th	Day	8% 5% 18% 26% 27% 16%	490
	21st to end	Day	18% 9% 24% 25% 16% 8%	490
October	1st to 10th	Day	19% 9% 25% 26% 16% 6%	490
	11th to 20th	Day	28% 16% 24% 25% 7% 1	490
	21st to end	Day	31% 15% 30% 18% 5% 1	463
November	1st to 10th	Day	25% 15% 30% 20% 9% 1	300
	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	13% 3 23% 40% 21% 2	412
June	1st to 10th	Night	16% 3 22% 43% 15% 2	380
	11th to 20th	Night	11% 4 23% 44% 18%	380
	21st to end	Night	12% 3 19% 43% 21% 1	380
July	1st to 10th	Night	7% 2 14% 51% 24% 3	370
	11th to 20th	Night	12% 2 18% 38% 26% 4	539
	21st to end	Night	9% 2 16% 47% 25% 2	624
August	1st to 10th	Night	10% 3 12% 39% 33% 3	567
	11th to 20th	Night	10% 3 15% 37% 30% 5%	564
	21st to end	Night	13% 4 17% 35% 28% 3	627
September	1st to 10th	Night	14% 5% 19% 36% 21% 5%	746
	11th to 20th	Night	12% 4 17% 34% 29% 5%	760
	21st to end	Night	20% 7% 21% 32% 16% 5%	760
October	1st to 10th	Night	21% 7% 26% 28% 16% 2	760
	11th to 20th	Night	29% 12% 24% 26% 9% 1	760
	21st to end	Night	34% 10% 29% 24% 3	836
November	1st to 10th	Night	27% 12% 26% 26% 8%	780
	11th to 20th	Night	29% 18% 31% 16% 5% 1	763
	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 2024-11-08 06:44:46. Version ac07

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