Bonanza Conservation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bonanza Conservation Area clear sky chart from 2005-11-06 to 2025-05-11.

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	11% 8% 3 7% 4 4 4 4 5% 7% 44%	114001
	Night	11% 7% 3 7% 4 4 4 3 5% 6% 46%	115144
Transparency	Day	39% 5% 12% 25% 17% 2	117650
	Night	37% 4 11% 25% 19% 3	119637
Seeing	Day	14% 10% 29% 27% 15% 4	16332
	Night	14% 9% 32% 32% 12% 1	26311

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	14% 9% 3 10% 4 5% 5% 4 5% 6% 35%	3985
	11th to 20th	Day	7% 10% 4 9% 6% 6% 7% 3 4 5% 39%	4080
	21st to end	Day	12% 14% 6% 11% 5% 4 4 3 3 4 33%	4488
February	1st to 10th	Day	14% 10% 5% 7% 4 4 5% 4 6% 8% 33%	1800
	11th to 20th	Day	12% 12% 4 7% 4 3 4 3 5% 7% 39%	1754
	21st to end	Day	11% 10% 3 7% 4 3 3 3 5% 7% 44%	1670
March	1st to 10th	Day	15% 9% 3 5% 3 2 3 3 4 4 49%	4936
	11th to 20th	Day	9% 7% 2 5% 4 3 4 3 5% 6% 52%	4980
	21st to end	Day	14% 11% 4 8% 5% 5% 5% 4 6% 7% 31%	5462
April	1st to 10th	Day	14% 8% 3 7% 4 3 4 3 5% 6% 43%	2354
	11th to 20th	Day	14% 9% 3 7% 4 4 4 4 5% 7% 40%	2374
	21st to end	Day	20% 8% 3 7% 4 4 5% 4 5% 7% 34%	2501
May	1st to 10th	Day	14% 8% 3 7% 5% 4 5% 4 6% 6% 39%	4212
	11th to 20th	Day	16% 8% 3 7% 5% 4 4 3 5% 7% 38%	4083
	21st to end	Day	12% 6% 2 6% 4 4 4 3 4 7% 46%	4820
June	1st to 10th	Day	7% 4 2 5% 5% 4 5% 4 7% 9% 47%	2660
	11th to 20th	Day	8% 5% 2 6% 5% 4 5% 4 7% 9% 46%	2660
	21st to end	Day	8% 4 2 5% 4 5% 5% 4 7% 9% 48%	2660
July	1st to 10th	Day	11% 7% 3 6% 5% 5% 5% 4 6% 9% 39%	4384
	11th to 20th	Day	6% 5% 2 5% 4 4 4 4 7% 8% 53%	4120
	21st to end	Day	5% 4 2 6% 4 5% 6% 5% 8% 10% 46%	4465
August	1st to 10th	Day	5% 4 1 6% 4 4 5% 4 7% 10% 51%	4104
	11th to 20th	Day	11% 5% 1 5% 4 5% 5% 4 6% 9% 46%	4041
	21st to end	Day	6% 4 2 5% 3 4 4 4 6% 8% 53%	4222
September	1st to 10th	Day	12% 4 2 4 3 3 3 3 4 7% 54%	2280
	11th to 20th	Day	9% 5% 1 5% 4 4 4 4 5% 8% 50%	2176
	21st to end	Day	10% 5% 2 4 4 4 4 3 5% 6% 55%	2040
October	1st to 10th	Day	12% 6% 2 4 3 3 3 3 5% 6% 52%	1900
	11th to 20th	Day	13% 7% 2 4 4 2 4 3 3 4 55%	1900
	21st to end	Day	14% 7% 3 5% 4 4 3 2 5% 6% 47%	2090
November	1st to 10th	Day	9% 6% 2 5% 4 3 3 3 5% 6% 53%	1958
	11th to 20th	Day	13% 7% 2 6% 4 3 3 3 5% 6% 49%	1642
	21st to end	Day	16% 11% 3 5% 4 3 2 2 5% 6% 43%	1600
December	1st to 10th	Day	6% 5% 3 6% 4 4 4 3 4 6% 54%	2610
	11th to 20th	Day	11% 8% 3 8% 5% 4 4 3 4 6% 46%	3008
	21st to end	Day	18% 16% 7% 13% 4 3 4 3 4 4 22%	3982
January	1st to 10th	Night	11% 10% 4 15% 6% 4 4 3 5% 5% 32%	5962
	11th to 20th	Night	9% 9% 4 9% 5% 5% 5% 4 6% 5% 39%	5900
	21st to end	Night	14% 9% 5% 11% 4 5% 4 3 3 5% 37%	6490
February	1st to 10th	Night	12% 10% 4 8% 5% 4 4 3 5% 6% 38%	2600
	11th to 20th	Night	12% 8% 4 8% 4 5% 4 3 5% 6% 41%	2533
	21st to end	Night	13% 8% 3 6% 3 3 3 3 5% 6% 47%	1975
March	1st to 10th	Night	15% 9% 3 5% 4 2 3 2 4 5% 48%	4919
	11th to 20th	Night	10% 7% 2 4 3 3 3 3 4 7% 54%	4980
	21st to end	Night	14% 9% 4 9% 5% 5% 5% 3 6% 7% 34%	5467
April	1st to 10th	Night	10% 7% 3 6% 4 4 3 3 4 7% 49%	2045
	11th to 20th	Night	13% 7% 2 6% 4 3 4 3 5% 6% 45%	1975
	21st to end	Night	16% 7% 2 7% 4 4 4 3 5% 6% 41%	1895
May	1st to 10th	Night	14% 6% 2 5% 4 4 4 4 6% 8% 41%	2913
	11th to 20th	Night	14% 7% 2 6% 4 4 4 4 5% 8% 41%	2828
	21st to end	Night	11% 5% 2 5% 3 4 4 3 5% 6% 52%	2746
June	1st to 10th	Night	6% 3 1 4 3 3 5% 4 8% 10% 53%	1520
	11th to 20th	Night	4 3 2 5% 5% 4 4 4 7% 11% 50%	1520
	21st to end	Night	5% 4 1 3 3 4 3 3 5% 11% 59%	1520
July	1st to 10th	Night	11% 7% 2 6% 4 4 4 3 6% 7% 47%	2581
	11th to 20th	Night	2 3 1 4 3 4 4 4 5% 9% 61%	2850
	21st to end	Night	5% 4 1 5% 4 5% 4 3 8% 11% 49%	3098
August	1st to 10th	Night	3 2 1 3 3 3 4 4 7% 10% 60%	2836
	11th to 20th	Night	11% 6% 2 5% 4 3 4 2 4 6% 54%	2798
	21st to end	Night	4 3 2 6% 4 3 4 3 5% 8% 59%	3435
September	1st to 10th	Night	9% 5% 1 4 3 3 4 3 4 6% 58%	1900
	11th to 20th	Night	10% 4 1 4 2 3 4 3 7% 8% 54%	2001
	21st to end	Night	7% 5% 2 5% 4 3 3 3 5% 7% 58%	2119
October	1st to 10th	Night	11% 5% 2 4 3 2 3 3 4 6% 57%	2280
	11th to 20th	Night	13% 4 2 5% 4 3 3 2 4 5% 56%	2280
	21st to end	Night	16% 7% 2 5% 4 3 2 2 4 5% 50%	2508
November	1st to 10th	Night	9% 5% 1 4 2 3 3 2 5% 6% 59%	2340
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 4 5% 52%	2755
	21st to end	Night	14% 9% 2 5% 4 3 3 3 4 5% 48%	2800
December	1st to 10th	Night	7% 6% 2 5% 4 4 4 3 5% 6% 53%	4580
	11th to 20th	Night	12% 8% 3 8% 3 3 3 3 5% 7% 44%	5199
	21st to end	Night	20% 16% 6% 10% 4 3 3 3 4 4 28%	6996

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	49% 5% 12% 23% 10% 1	3986
	11th to 20th	Day	48% 4 11% 19% 14% 4	4080
	21st to end	Day	55% 4 10% 15% 15% 2	4488
February	1st to 10th	Day	50% 5% 13% 20% 10% 3	1800
	11th to 20th	Day	46% 5% 12% 22% 13% 2	1763
	21st to end	Day	40% 5% 11% 22% 19% 3	1670
March	1st to 10th	Day	39% 3 8% 23% 22% 4	4936
	11th to 20th	Day	33% 4 8% 24% 26% 5%	4980
	21st to end	Day	51% 6% 16% 22% 5% 1	5464
April	1st to 10th	Day	42% 6% 11% 25% 15% 2	2354
	11th to 20th	Day	44% 5% 12% 23% 15% 1	2374
	21st to end	Day	50% 6% 11% 22% 10% 1	2501
May	1st to 10th	Day	43% 7% 11% 23% 14% 1	4250
	11th to 20th	Day	45% 7% 12% 24% 12%	4087
	21st to end	Day	37% 6% 10% 29% 16% 2	4833
June	1st to 10th	Day	31% 9% 15% 30% 14% 2	2660
	11th to 20th	Day	32% 7% 14% 27% 18% 1	2660
	21st to end	Day	31% 7% 16% 28% 14% 3	2660
July	1st to 10th	Day	41% 6% 13% 24% 12% 3	4316
	11th to 20th	Day	28% 6% 11% 35% 18% 2	4051
	21st to end	Day	30% 7% 17% 30% 13% 2	4325
August	1st to 10th	Day	27% 6% 15% 31% 20% 1	4090
	11th to 20th	Day	35% 5% 15% 28% 16% 1	4080
	21st to end	Day	27% 6% 16% 31% 13% 6%	4221
September	1st to 10th	Day	30% 6% 11% 27% 20% 6%	2280
	11th to 20th	Day	31% 6% 12% 26% 22% 2	2176
	21st to end	Day	31% 5% 8% 31% 22% 3	2040
October	1st to 10th	Day	20% 3 6% 22% 43% 5%	3160
	11th to 20th	Day	22% 2 5% 23% 38% 9%	3140
	21st to end	Day	34% 3 11% 25% 25% 3	3428
November	1st to 10th	Day	32% 4 14% 27% 19% 4	1958
	11th to 20th	Day	36% 4 11% 27% 20% 3	1642
	21st to end	Day	43% 3 9% 28% 16%	1600
December	1st to 10th	Day	32% 4 16% 30% 18%	2610
	11th to 20th	Day	41% 4 14% 29% 11% 1	3005
	21st to end	Day	66% 3 12% 12% 6% 1	3982
January	1st to 10th	Night	53% 4 10% 22% 10% 1	5962
	11th to 20th	Night	46% 4 10% 21% 15% 4	5900
	21st to end	Night	51% 3 10% 16% 15% 4	6490
February	1st to 10th	Night	47% 6% 10% 20% 14% 3	2600
	11th to 20th	Night	44% 5% 11% 21% 16% 3	2534
	21st to end	Night	38% 4 9% 23% 21% 5%	1975
March	1st to 10th	Night	40% 3 7% 23% 23% 4	4919
	11th to 20th	Night	31% 4 6% 27% 26% 7%	4980
	21st to end	Night	48% 6% 14% 23% 8% 2	5467
April	1st to 10th	Night	37% 4 10% 26% 19% 4	2045
	11th to 20th	Night	40% 5% 9% 27% 16% 3	1975
	21st to end	Night	44% 5% 10% 25% 15% 1	1895
May	1st to 10th	Night	39% 8% 13% 23% 16% 1	2940
	11th to 20th	Night	40% 8% 10% 29% 13% 1	2829
	21st to end	Night	33% 6% 11% 27% 22% 2	2754
June	1st to 10th	Night	23% 8% 17% 32% 16% 3	1520
	11th to 20th	Night	27% 7% 13% 29% 20% 3	1520
	21st to end	Night	21% 6% 15% 34% 20% 4	1520
July	1st to 10th	Night	36% 5% 11% 24% 20% 3	2540
	11th to 20th	Night	19% 6% 15% 37% 21% 2	2796
	21st to end	Night	28% 6% 21% 32% 13% 1	2999
August	1st to 10th	Night	18% 5% 20% 30% 26% 2	2826
	11th to 20th	Night	33% 4 12% 28% 22% 1	2825
	21st to end	Night	25% 4 16% 34% 17% 5%	3435
September	1st to 10th	Night	28% 5% 9% 27% 24% 8%	1900
	11th to 20th	Night	26% 5% 11% 29% 24% 4	2001
	21st to end	Night	27% 5% 8% 30% 26% 4	2119
October	1st to 10th	Night	18% 3 6% 19% 48% 6%	3800
	11th to 20th	Night	22% 2 7% 24% 34% 12%	3779
	21st to end	Night	36% 3 7% 27% 25% 2	4120
November	1st to 10th	Night	27% 4 14% 26% 22% 6%	2340
	11th to 20th	Night	34% 4 8% 28% 21% 5%	2755
	21st to end	Night	39% 3 10% 28% 17% 3	2800
December	1st to 10th	Night	33% 3 13% 36% 15% 1	4580
	11th to 20th	Night	40% 4 14% 27% 14% 1	5201
	21st to end	Night	62% 3 11% 18% 6% 1	6996

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% 14% 37% 21% 6%	300
	11th to 20th	Day	23% 17% 42% 16% 2	300
	21st to end	Day	15% 15% 45% 22% 3	330
February	1st to 10th	Day	21% 21% 40% 16% 2	300
	11th to 20th	Day	20% 18% 43% 13% 7%	300
	21st to end	Day	15% 22% 39% 20% 3	249
March	1st to 10th	Day	18% 16% 46% 16% 3	300
	11th to 20th	Day	27% 15% 33% 21% 4	300
	21st to end	Day	37% 16% 30% 14% 2	330
April	1st to 10th	Day	21% 17% 36% 18% 7%	454
	11th to 20th	Day	19% 17% 37% 21% 6% 1	492
	21st to end	Day	23% 17% 32% 19% 8% 1	601
May	1st to 10th	Day	17% 14% 35% 24% 9% 1	703
	11th to 20th	Day	20% 12% 28% 27% 12% 2	676
	21st to end	Day	16% 7% 30% 26% 18% 3	734
June	1st to 10th	Day	6% 4 21% 36% 24% 8%	680
	11th to 20th	Day	8% 5% 25% 37% 20% 5%	680
	21st to end	Day	7% 6% 35% 33% 16% 2	680
July	1st to 10th	Day	10% 3 17% 31% 29% 12%	671
	11th to 20th	Day	6% 3 21% 36% 26% 8%	668
	21st to end	Day	6% 2 17% 38% 29% 7%	739
August	1st to 10th	Day	7% 2 20% 37% 27% 7%	676
	11th to 20th	Day	9% 4 18% 34% 29% 7%	665
	21st to end	Day	9% 2 14% 31% 32% 12%	568
September	1st to 10th	Day	13% 3 14% 33% 29% 7%	490
	11th to 20th	Day	8% 4 18% 36% 26% 8%	386
	21st to end	Day	12% 8% 27% 28% 20% 6%	300
October	1st to 10th	Day	16% 7% 26% 28% 16% 7%	300
	11th to 20th	Day	11% 23% 35% 22% 8% 1	300
	21st to end	Day	20% 18% 34% 22% 6%	330
November	1st to 10th	Day	16% 9% 42% 24% 7% 3	300
	11th to 20th	Day	17% 19% 34% 23% 5% 3	300
	21st to end	Day	23% 17% 28% 25% 7%	300
December	1st to 10th	Day	10% 19% 38% 24% 7% 3	300
	11th to 20th	Day	20% 17% 36% 21% 5% 1	300
	21st to end	Day	22% 22% 36% 18% 2	330
January	1st to 10th	Night	15% 13% 40% 26% 7%	1000
	11th to 20th	Night	16% 15% 40% 22% 6% 1	1000
	21st to end	Night	17% 12% 40% 29% 3	1100
February	1st to 10th	Night	18% 12% 44% 24% 4	1000
	11th to 20th	Night	17% 14% 38% 27% 4	979
	21st to end	Night	18% 15% 43% 19% 4 1	655
March	1st to 10th	Night	18% 12% 39% 26% 5%	600
	11th to 20th	Night	19% 11% 36% 27% 6% 1	600
	21st to end	Night	26% 12% 38% 20% 5%	660
April	1st to 10th	Night	13% 13% 42% 27% 4	600
	11th to 20th	Night	18% 15% 35% 26% 6%	593
	21st to end	Night	20% 11% 36% 27% 6% 1	600
May	1st to 10th	Night	16% 9% 36% 31% 8% 1	600
	11th to 20th	Night	18% 7% 26% 34% 14% 1	563
	21st to end	Night	12% 6% 27% 37% 16% 2	617
June	1st to 10th	Night	6% 3 22% 45% 21% 3	570
	11th to 20th	Night	6% 3 25% 48% 17% 2	570
	21st to end	Night	5% 3 28% 47% 16%	570
July	1st to 10th	Night	8% 2 13% 41% 32% 4	555
	11th to 20th	Night	3 2 16% 48% 30% 2	552
	21st to end	Night	6% 2 13% 42% 34% 3	624
August	1st to 10th	Night	4 1 16% 47% 29% 1	567
	11th to 20th	Night	7% 2 14% 43% 31% 3	564
	21st to end	Night	6% 2 14% 42% 33% 3	627
September	1st to 10th	Night	11% 2 17% 38% 27% 4	570
	11th to 20th	Night	12% 2 19% 39% 25% 4	570
	21st to end	Night	9% 5% 23% 39% 21% 3	599
October	1st to 10th	Night	13% 5% 28% 35% 17% 2	760
	11th to 20th	Night	15% 9% 35% 30% 10%	760
	21st to end	Night	20% 12% 32% 28% 7%	836
November	1st to 10th	Night	12% 10% 34% 34% 9% 1	780
	11th to 20th	Night	15% 14% 37% 26% 8%	970
	21st to end	Night	19% 12% 36% 26% 7%	1000
December	1st to 10th	Night	16% 13% 36% 27% 7% 1	1000
	11th to 20th	Night	19% 10% 39% 26% 6%	1000
	21st to end	Night	21% 16% 33% 26% 3	1100

Page generated at 2025-05-08 08:33:55. Version ac07

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