Berrysville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Berrysville clear sky chart from 2005-11-06 to 2025-04-11.

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% 9% 3 8% 5% 4 4 4 5% 7% 35%	114168
	Night	15% 10% 4 8% 5% 4 4 3 5% 7% 36%	114105
Transparency	Day	46% 6% 10% 22% 14% 2	117873
	Night	46% 5% 10% 22% 15% 2	118526
Seeing	Day	18% 13% 27% 22% 14% 6%	15558
	Night	18% 10% 27% 28% 15% 2	25464

By Month

Percentage Cloud Cover SE (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	15% 18% 8% 14% 5% 4 3 3 4 6% 21%	4056
	11th to 20th	Day	14% 16% 6% 14% 6% 6% 4 4 4 3 23%	4060
	21st to end	Day	22% 13% 7% 9% 6% 6% 4 3 4 4 22%	4466
February	1st to 10th	Day	20% 13% 5% 9% 5% 4 4 4 4 5% 27%	1848
	11th to 20th	Day	19% 13% 4 10% 5% 4 4 3 4 6% 27%	1948
	21st to end	Day	20% 12% 4 10% 5% 3 4 2 4 6% 30%	1650
March	1st to 10th	Day	17% 13% 7% 9% 4 4 4 3 4 5% 30%	4618
	11th to 20th	Day	12% 8% 3 7% 5% 4 5% 4 6% 7% 39%	4980
	21st to end	Day	17% 10% 3 8% 5% 4 4 4 5% 7% 34%	5465
April	1st to 10th	Day	15% 11% 3 7% 5% 4 4 4 5% 7% 35%	2285
	11th to 20th	Day	17% 8% 2 7% 4 4 3 4 5% 7% 38%	2352
	21st to end	Day	19% 8% 2 7% 6% 5% 4 3 5% 7% 35%	2470
May	1st to 10th	Day	21% 10% 3 7% 5% 4 4 4 5% 6% 32%	4082
	11th to 20th	Day	21% 9% 2 6% 4 4 4 3 6% 7% 33%	4081
	21st to end	Day	11% 6% 3 7% 5% 5% 6% 6% 8% 10% 34%	4476
June	1st to 10th	Day	12% 5% 2 6% 5% 5% 5% 4 7% 9% 40%	2470
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 4 7% 9% 42%	2470
	21st to end	Day	9% 6% 3 6% 5% 4 5% 4 8% 10% 40%	2639
July	1st to 10th	Day	12% 6% 3 7% 5% 5% 5% 4 6% 9% 40%	4280
	11th to 20th	Day	8% 5% 2 6% 4 5% 5% 5% 7% 10% 44%	4120
	21st to end	Day	11% 8% 3 8% 6% 6% 6% 5% 8% 8% 30%	4466
August	1st to 10th	Day	7% 5% 2 6% 5% 5% 5% 4 7% 11% 42%	4104
	11th to 20th	Day	7% 6% 2 7% 5% 5% 5% 5% 8% 10% 40%	4044
	21st to end	Day	5% 4 2 5% 4 4 5% 4 6% 9% 53%	4322
September	1st to 10th	Day	14% 5% 2 5% 4 4 4 3 5% 7% 48%	2119
	11th to 20th	Day	9% 5% 1 5% 4 4 4 4 6% 8% 49%	2090
	21st to end	Day	18% 7% 2 6% 4 4 3 3 4 6% 44%	2090
October	1st to 10th	Day	12% 5% 2 4 4 4 4 4 6% 7% 48%	2076
	11th to 20th	Day	14% 7% 2 5% 5% 3 4 3 4 6% 46%	1900
	21st to end	Day	20% 8% 3 6% 4 3 3 3 4 6% 40%	2010
November	1st to 10th	Day	11% 7% 2 6% 4 3 4 3 5% 6% 49%	1762
	11th to 20th	Day	15% 12% 4 8% 4 4 4 3 5% 6% 36%	1800
	21st to end	Day	18% 11% 4 8% 5% 4 4 3 4 6% 34%	1800
December	1st to 10th	Day	18% 13% 3 8% 4 4 5% 3 3 5% 34%	2930
	11th to 20th	Day	21% 14% 5% 9% 5% 5% 4 4 5% 5% 24%	3373
	21st to end	Day	20% 19% 5% 12% 5% 4 4 3 4 5% 19%	4466
January	1st to 10th	Night	15% 17% 6% 15% 7% 5% 5% 4 4 4 18%	5889
	11th to 20th	Night	15% 16% 7% 14% 7% 4 5% 3 4 4 22%	5900
	21st to end	Night	20% 12% 5% 9% 4 5% 4 2 3 5% 30%	6490
February	1st to 10th	Night	20% 14% 4 8% 5% 3 4 3 5% 5% 28%	2550
	11th to 20th	Night	19% 12% 4 9% 6% 4 5% 3 4 5% 30%	2338
	21st to end	Night	21% 13% 5% 8% 5% 4 3 3 3 6% 29%	1980
March	1st to 10th	Night	18% 13% 3 6% 4 4 4 3 4 5% 36%	5221
	11th to 20th	Night	12% 7% 3 6% 4 3 4 4 6% 9% 42%	4980
	21st to end	Night	17% 9% 4 8% 6% 5% 4 4 4 6% 33%	5467
April	1st to 10th	Night	15% 9% 3 6% 5% 5% 5% 4 7% 7% 36%	2131
	11th to 20th	Night	14% 7% 3 7% 4 3 5% 4 6% 7% 40%	1783
	21st to end	Night	16% 9% 3 6% 4 4 4 4 6% 7% 37%	1710
May	1st to 10th	Night	24% 11% 3 7% 4 4 4 3 5% 6% 28%	2813
	11th to 20th	Night	18% 8% 2 5% 4 3 4 3 6% 9% 38%	2812
	21st to end	Night	9% 5% 2 5% 4 3 4 5% 7% 10% 45%	3079
June	1st to 10th	Night	8% 5% 2 5% 5% 5% 4 4 6% 9% 48%	1710
	11th to 20th	Night	8% 4 2 5% 4 4 4 4 6% 11% 48%	1710
	21st to end	Night	7% 5% 2 4 4 4 4 5% 9% 12% 45%	1527
July	1st to 10th	Night	9% 5% 2 6% 4 4 4 3 6% 8% 48%	2675
	11th to 20th	Night	7% 4 2 6% 4 4 4 4 5% 10% 49%	2840
	21st to end	Night	10% 7% 2 8% 6% 6% 5% 5% 6% 8% 39%	3087
August	1st to 10th	Night	6% 6% 2 7% 5% 5% 5% 4 6% 9% 44%	2825
	11th to 20th	Night	9% 7% 3 8% 6% 5% 5% 3 5% 7% 43%	2785
	21st to end	Night	4 2 1 4 3 4 3 4 7% 11% 57%	3316
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 5% 7% 51%	2042
	11th to 20th	Night	9% 4 2 5% 4 3 4 3 4 7% 55%	2090
	21st to end	Night	13% 6% 1 6% 4 4 3 3 6% 5% 48%	2090
October	1st to 10th	Night	9% 4 2 5% 4 4 4 3 5% 6% 54%	2103
	11th to 20th	Night	15% 6% 2 5% 3 4 4 3 5% 6% 47%	2280
	21st to end	Night	18% 8% 2 5% 4 4 4 3 5% 5% 41%	2584
November	1st to 10th	Night	14% 6% 2 6% 3 3 3 4 5% 7% 47%	2536
	11th to 20th	Night	15% 10% 3 6% 5% 4 4 3 5% 6% 39%	2600
	21st to end	Night	19% 13% 3 6% 5% 4 4 3 5% 6% 32%	2600
December	1st to 10th	Night	17% 11% 4 8% 4 3 3 2 4 5% 37%	4250
	11th to 20th	Night	19% 14% 6% 9% 5% 4 4 3 5% 5% 26%	4822
	21st to end	Night	21% 19% 6% 10% 6% 5% 4 3 4 6% 18%	6490

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	64% 4 9% 15% 6%	4057
	11th to 20th	Day	63% 5% 8% 13% 9% 2	4060
	21st to end	Day	65% 4 8% 16% 6% 1	4466
February	1st to 10th	Day	59% 4 10% 17% 9% 1	1848
	11th to 20th	Day	59% 4 10% 17% 10% 1	1958
	21st to end	Day	57% 4 9% 21% 9% 2	1650
March	1st to 10th	Day	55% 4 6% 22% 11% 2	4618
	11th to 20th	Day	42% 5% 9% 28% 14% 1	4980
	21st to end	Day	49% 5% 10% 22% 12% 2	5465
April	1st to 10th	Day	47% 6% 12% 23% 11% 2	2285
	11th to 20th	Day	45% 5% 9% 22% 15% 3	2352
	21st to end	Day	49% 5% 11% 21% 12% 2	2470
May	1st to 10th	Day	52% 6% 11% 22% 8% 1	4120
	11th to 20th	Day	49% 7% 11% 20% 12% 1	4085
	21st to end	Day	40% 10% 15% 17% 16% 2	4489
June	1st to 10th	Day	39% 9% 11% 24% 15% 2	2470
	11th to 20th	Day	36% 9% 15% 23% 16% 1	2470
	21st to end	Day	37% 9% 13% 23% 14% 4	2639
July	1st to 10th	Day	41% 7% 11% 22% 17% 2	4215
	11th to 20th	Day	32% 8% 12% 32% 16% 1	4051
	21st to end	Day	48% 8% 11% 17% 13% 2	4324
August	1st to 10th	Day	33% 8% 14% 32% 11% 1	4091
	11th to 20th	Day	35% 7% 11% 29% 16% 1	4083
	21st to end	Day	27% 6% 15% 28% 21% 3	4321
September	1st to 10th	Day	36% 6% 11% 23% 19% 6%	2119
	11th to 20th	Day	31% 7% 13% 23% 23% 3	2090
	21st to end	Day	41% 6% 9% 22% 20% 2	2090
October	1st to 10th	Day	23% 4 9% 30% 32% 2	3453
	11th to 20th	Day	30% 4 8% 31% 26% 2	3140
	21st to end	Day	35% 4 10% 26% 23% 3	3286
November	1st to 10th	Day	35% 6% 9% 28% 19% 2	1762
	11th to 20th	Day	49% 4 7% 22% 15% 4	1800
	21st to end	Day	52% 4 10% 21% 13% 1	1800
December	1st to 10th	Day	54% 5% 9% 24% 8%	2930
	11th to 20th	Day	61% 6% 8% 18% 7%	3370
	21st to end	Day	68% 4 9% 13% 5% 1	4466
January	1st to 10th	Night	68% 6% 7% 13% 7%	5889
	11th to 20th	Night	66% 4 8% 12% 8% 2	5900
	21st to end	Night	57% 5% 8% 20% 9% 1	6490
February	1st to 10th	Night	57% 5% 10% 18% 9% 1	2550
	11th to 20th	Night	56% 4 8% 18% 12% 1	2339
	21st to end	Night	57% 3 9% 17% 10% 2	1980
March	1st to 10th	Night	49% 4 6% 26% 12% 2	5221
	11th to 20th	Night	38% 6% 9% 30% 16% 1	4980
	21st to end	Night	52% 5% 7% 22% 12% 1	5467
April	1st to 10th	Night	45% 6% 10% 24% 13% 2	2131
	11th to 20th	Night	42% 5% 10% 19% 18% 6%	1783
	21st to end	Night	45% 6% 11% 23% 14% 3	1710
May	1st to 10th	Night	56% 6% 9% 19% 9% 2	2840
	11th to 20th	Night	43% 8% 13% 25% 10% 1	2813
	21st to end	Night	31% 8% 15% 26% 14% 5%	3087
June	1st to 10th	Night	32% 7% 13% 26% 19% 3	1710
	11th to 20th	Night	29% 8% 17% 23% 20% 4	1710
	21st to end	Night	29% 9% 19% 23% 17% 3	1527
July	1st to 10th	Night	34% 6% 12% 24% 19% 5%	2631
	11th to 20th	Night	29% 7% 14% 30% 18% 1	2786
	21st to end	Night	40% 9% 12% 21% 14% 4	2988
August	1st to 10th	Night	33% 8% 14% 31% 11% 1	2814
	11th to 20th	Night	38% 8% 10% 25% 18% 1	2812
	21st to end	Night	21% 7% 17% 30% 22% 3	3316
September	1st to 10th	Night	32% 6% 12% 24% 20% 7%	2042
	11th to 20th	Night	29% 6% 10% 24% 27% 3	2090
	21st to end	Night	37% 5% 9% 20% 26% 2	2090
October	1st to 10th	Night	23% 4 8% 26% 36% 3	3506
	11th to 20th	Night	28% 4 8% 27% 30% 4	3779
	21st to end	Night	33% 3 9% 22% 26% 7%	4245
November	1st to 10th	Night	37% 4 10% 24% 22% 3	2536
	11th to 20th	Night	46% 4 8% 21% 18% 4	2600
	21st to end	Night	53% 4 10% 20% 11% 2	2600
December	1st to 10th	Night	51% 3 11% 24% 10% 1	4250
	11th to 20th	Night	59% 4 11% 19% 7% 1	4824
	21st to end	Night	68% 4 8% 15% 4	6490

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	23% 26% 34% 13% 4	300
	11th to 20th	Day	28% 25% 34% 11% 1	300
	21st to end	Day	29% 24% 33% 11% 3	330
February	1st to 10th	Day	28% 23% 33% 11% 4	300
	11th to 20th	Day	32% 27% 32% 6% 2	300
	21st to end	Day	31% 20% 40% 8%	249
March	1st to 10th	Day	26% 26% 31% 14% 4	360
	11th to 20th	Day	25% 21% 33% 17% 4	500
	21st to end	Day	32% 19% 29% 16% 5%	550
April	1st to 10th	Day	22% 20% 32% 16% 9% 1	500
	11th to 20th	Day	23% 22% 24% 19% 9% 3	452
	21st to end	Day	22% 17% 36% 14% 8% 2	460
May	1st to 10th	Day	25% 16% 29% 18% 8% 3	463
	11th to 20th	Day	19% 10% 29% 22% 14% 5%	487
	21st to end	Day	12% 9% 25% 27% 19% 8%	529
June	1st to 10th	Day	13% 8% 21% 31% 19% 8%	490
	11th to 20th	Day	11% 6% 23% 33% 20% 7%	490
	21st to end	Day	9% 7% 29% 30% 17% 8%	659
July	1st to 10th	Day	13% 5% 17% 24% 20% 20%	580
	11th to 20th	Day	9% 5% 22% 27% 24% 12%	484
	21st to end	Day	12% 2 20% 30% 22% 14%	532
August	1st to 10th	Day	12% 4 16% 28% 25% 16%	486
	11th to 20th	Day	10% 4 22% 33% 20% 10%	479
	21st to end	Day	8% 3 14% 33% 25% 15%	539
September	1st to 10th	Day	12% 5% 17% 28% 27% 11%	490
	11th to 20th	Day	9% 3 17% 27% 31% 13%	490
	21st to end	Day	22% 8% 20% 23% 22% 4	490
October	1st to 10th	Day	11% 7% 25% 32% 17% 8%	490
	11th to 20th	Day	14% 14% 34% 20% 12% 5%	490
	21st to end	Day	23% 15% 31% 24% 7% 1	459
November	1st to 10th	Day	15% 14% 36% 25% 8% 2	300
	11th to 20th	Day	22% 20% 30% 20% 6% 2	300
	21st to end	Day	24% 20% 34% 17% 4	300
December	1st to 10th	Day	25% 22% 34% 13% 6%	300
	11th to 20th	Day	21% 24% 36% 15% 4	300
	21st to end	Day	26% 24% 32% 15% 3	330
January	1st to 10th	Night	24% 21% 32% 20% 4	800
	11th to 20th	Night	28% 18% 34% 19% 2	800
	21st to end	Night	24% 17% 34% 22% 3	880
February	1st to 10th	Night	29% 13% 34% 22% 2	800
	11th to 20th	Night	27% 19% 33% 19% 2	783
	21st to end	Night	28% 16% 34% 21% 2	660
March	1st to 10th	Night	20% 18% 33% 24% 5%	800
	11th to 20th	Night	21% 17% 35% 20% 7%	800
	21st to end	Night	23% 13% 32% 25% 7%	880
April	1st to 10th	Night	19% 15% 35% 24% 6%	731
	11th to 20th	Night	17% 12% 34% 25% 11% 1	565
	21st to end	Night	18% 8% 39% 27% 6% 1	570
May	1st to 10th	Night	20% 9% 30% 28% 12% 1	570
	11th to 20th	Night	17% 7% 25% 32% 18% 1	561
	21st to end	Night	8% 4 23% 34% 26% 5%	617
June	1st to 10th	Night	9% 2 24% 41% 23% 2	570
	11th to 20th	Night	9% 4 17% 42% 25% 4	570
	21st to end	Night	6% 3 24% 37% 27% 2	570
July	1st to 10th	Night	11% 3 14% 32% 30% 10%	555
	11th to 20th	Night	6% 2 15% 37% 36% 4	552
	21st to end	Night	11% 2 12% 39% 33% 4	624
August	1st to 10th	Night	8% 2 12% 40% 34% 5%	567
	11th to 20th	Night	9% 3 13% 40% 30% 5%	564
	21st to end	Night	6% 1 14% 36% 34% 9%	627
September	1st to 10th	Night	13% 3 14% 33% 31% 6%	712
	11th to 20th	Night	10% 3 14% 32% 35% 6%	760
	21st to end	Night	15% 5% 18% 36% 24% 2	760
October	1st to 10th	Night	11% 6% 23% 34% 23% 4	760
	11th to 20th	Night	18% 9% 27% 31% 13% 2	760
	21st to end	Night	21% 12% 28% 28% 11% 1	836
November	1st to 10th	Night	17% 9% 29% 27% 17% 1	780
	11th to 20th	Night	20% 16% 29% 25% 9% 1	800
	21st to end	Night	24% 14% 28% 28% 6% 1	800
December	1st to 10th	Night	27% 16% 30% 22% 5%	800
	11th to 20th	Night	25% 13% 32% 23% 6% 1	800
	21st to end	Night	29% 15% 30% 23% 3	880

Page generated at 2025-04-08 09:17:29. Version ac07

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