Boonville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Boonville clear sky chart from 2005-11-06 to 2026-08-15.

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	12% 7% 3 6% 4 4 4 3 5% 7% 43%	143854
	Night	12% 8% 3 7% 4 4 4 3 5% 6% 45%	138360
Transparency	Day	40% 3 12% 26% 16% 2	147458
	Night	40% 3 11% 25% 18% 3	142835
Seeing	Day	15% 9% 26% 28% 17% 5%	18137
	Night	15% 8% 29% 33% 14% 1	27881

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	13% 13% 4 9% 4 4 4 3 4 5% 36%	4973
	11th to 20th	Day	7% 8% 4 9% 5% 7% 5% 4 4 6% 42%	5310
	21st to end	Day	15% 13% 4 8% 4 3 4 3 3 4 38%	5812
February	1st to 10th	Day	16% 9% 4 9% 5% 3 4 2 5% 7% 35%	1890
	11th to 20th	Day	14% 10% 4 7% 4 4 4 3 4 5% 41%	1869
	21st to end	Day	14% 10% 3 6% 5% 3 4 3 5% 5% 41%	1731
March	1st to 10th	Day	16% 9% 3 4 3 2 3 2 3 5% 50%	5046
	11th to 20th	Day	10% 7% 2 5% 3 3 3 3 4 7% 53%	5090
	21st to end	Day	15% 11% 4 8% 6% 4 4 4 6% 7% 33%	5618
April	1st to 10th	Day	15% 7% 3 7% 5% 4 3 3 6% 6% 42%	2520
	11th to 20th	Day	15% 9% 2 6% 4 4 5% 3 4 6% 41%	2494
	21st to end	Day	20% 7% 2 7% 4 5% 5% 4 5% 6% 34%	2520
May	1st to 10th	Day	15% 7% 2 6% 4 4 4 4 6% 9% 38%	7557
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 5% 7% 43%	7861
	21st to end	Day	18% 8% 3 7% 4 4 4 3 5% 7% 36%	9047
June	1st to 10th	Day	8% 4 2 5% 5% 5% 5% 4 7% 10% 45%	2940
	11th to 20th	Day	8% 5% 2 6% 4 4 4 4 6% 9% 46%	2940
	21st to end	Day	6% 5% 2 5% 5% 4 5% 4 7% 9% 47%	2940
July	1st to 10th	Day	10% 5% 2 6% 4 4 4 4 6% 9% 46%	8280
	11th to 20th	Day	7% 5% 2 5% 4 4 5% 4 6% 10% 48%	7842
	21st to end	Day	10% 5% 2 5% 4 5% 5% 4 8% 11% 41%	8337
August	1st to 10th	Day	4 4 2 4 5% 4 5% 4 8% 11% 50%	4364
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 6% 8% 46%	4130
	21st to end	Day	6% 4 2 4 4 3 5% 4 7% 9% 53%	4312
September	1st to 10th	Day	10% 5% 2 4 4 4 4 2 5% 8% 52%	2400
	11th to 20th	Day	9% 5% 2 6% 4 4 4 3 5% 8% 51%	2391
	21st to end	Day	8% 5% 2 5% 4 4 4 4 5% 7% 52%	2090
October	1st to 10th	Day	11% 4 2 6% 3 3 3 3 5% 5% 55%	2000
	11th to 20th	Day	13% 8% 2 4 3 2 3 2 4 6% 53%	2000
	21st to end	Day	17% 8% 3 6% 3 3 3 2 3 5% 47%	2200
November	1st to 10th	Day	11% 6% 2 5% 4 3 3 3 5% 5% 53%	1995
	11th to 20th	Day	14% 7% 2 6% 3 3 3 3 4 7% 49%	1827
	21st to end	Day	18% 10% 3 7% 3 3 3 2 4 5% 42%	1680
December	1st to 10th	Day	8% 9% 3 6% 4 3 4 2 4 7% 50%	2690
	11th to 20th	Day	12% 9% 4 8% 4 3 3 2 4 5% 45%	3088
	21st to end	Day	21% 18% 6% 10% 4 4 4 3 4 4 22%	4070
January	1st to 10th	Night	13% 11% 5% 12% 5% 4 3 3 3 4 36%	7932
	11th to 20th	Night	10% 8% 4 10% 5% 5% 4 3 4 4 43%	7680
	21st to end	Night	14% 13% 4 7% 5% 5% 4 3 4 5% 37%	8402
February	1st to 10th	Night	15% 10% 4 8% 6% 4 4 4 5% 6% 36%	2730
	11th to 20th	Night	14% 10% 4 6% 5% 3 5% 3 4 6% 40%	2637
	21st to end	Night	14% 10% 4 6% 4 3 3 2 4 5% 45%	2076
March	1st to 10th	Night	17% 10% 3 6% 3 3 3 3 4 4 45%	5058
	11th to 20th	Night	11% 7% 2 5% 3 3 3 3 5% 6% 52%	5090
	21st to end	Night	15% 11% 3 8% 5% 5% 4 3 5% 6% 35%	5552
April	1st to 10th	Night	12% 7% 2 6% 4 4 3 3 4 7% 47%	2100
	11th to 20th	Night	15% 7% 2 6% 4 4 4 3 5% 7% 44%	2075
	21st to end	Night	18% 7% 3 6% 4 3 4 3 4 6% 41%	2100
May	1st to 10th	Night	16% 7% 3 7% 4 4 4 3 6% 7% 39%	5307
	11th to 20th	Night	11% 5% 2 6% 4 4 4 3 5% 9% 46%	5028
	21st to end	Night	16% 7% 3 7% 4 4 4 3 5% 8% 39%	5139
June	1st to 10th	Night	7% 4 1 5% 4 4 4 4 6% 8% 52%	1680
	11th to 20th	Night	5% 5% 2 6% 5% 4 4 4 8% 11% 48%	1680
	21st to end	Night	4 3 1 4 4 4 4 4 6% 9% 56%	1680
July	1st to 10th	Night	8% 5% 2 6% 3 3 4 3 5% 10% 50%	4708
	11th to 20th	Night	5% 4 2 5% 4 4 4 4 6% 9% 53%	5127
	21st to end	Night	7% 4 2 6% 4 4 5% 4 7% 11% 46%	5770
August	1st to 10th	Night	4 2 1 3 3 3 4 3 6% 9% 61%	3016
	11th to 20th	Night	11% 5% 2 5% 3 3 3 4 5% 8% 51%	3012
	21st to end	Night	4 3 1 4 3 4 4 4 6% 8% 58%	3586
September	1st to 10th	Night	10% 4 2 4 3 3 3 3 4 6% 58%	2000
	11th to 20th	Night	9% 4 1 5% 3 4 5% 4 6% 7% 51%	2005
	21st to end	Night	8% 5% 2 5% 3 3 3 3 4 6% 56%	2290
October	1st to 10th	Night	8% 5% 1 4 3 3 3 3 5% 6% 59%	2400
	11th to 20th	Night	15% 4 2 5% 3 3 3 2 4 5% 53%	2400
	21st to end	Night	16% 8% 2 5% 3 3 3 3 4 5% 48%	2640
November	1st to 10th	Night	10% 5% 2 4 4 3 4 3 4 5% 56%	2521
	11th to 20th	Night	11% 7% 2 5% 4 3 3 3 4 7% 50%	2790
	21st to end	Night	17% 10% 2 6% 4 3 3 3 4 5% 45%	2940
December	1st to 10th	Night	9% 8% 3 6% 4 3 3 3 5% 6% 50%	4720
	11th to 20th	Night	16% 9% 3 6% 3 3 4 3 4 6% 43%	5339
	21st to end	Night	23% 16% 5% 9% 4 4 3 3 3 4 26%	7150

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	52% 3 10% 23% 11% 1	4974
	11th to 20th	Day	46% 1 10% 24% 15% 4	5310
	21st to end	Day	52% 1 10% 17% 16% 3	5812
February	1st to 10th	Day	51% 3 11% 22% 11% 1	1890
	11th to 20th	Day	47% 3 11% 21% 15% 3	1878
	21st to end	Day	45% 3 8% 25% 16% 3	1731
March	1st to 10th	Day	40% 2 7% 24% 24% 3	5046
	11th to 20th	Day	34% 3 9% 25% 24% 6%	5090
	21st to end	Day	51% 3 16% 25% 5%	5620
April	1st to 10th	Day	44% 4 11% 25% 15% 2	2520
	11th to 20th	Day	44% 4 11% 24% 14% 2	2494
	21st to end	Day	50% 4 13% 22% 11% 1	2520
May	1st to 10th	Day	44% 4 14% 26% 13%	7595
	11th to 20th	Day	43% 3 11% 26% 15% 2	7865
	21st to end	Day	49% 4 9% 25% 14% 1	9061
June	1st to 10th	Day	33% 6% 16% 30% 15% 1	2940
	11th to 20th	Day	33% 6% 13% 28% 17% 3	2940
	21st to end	Day	32% 6% 16% 28% 14% 4	2940
July	1st to 10th	Day	37% 3 13% 27% 19% 1	8211
	11th to 20th	Day	34% 3 16% 28% 16% 3	7770
	21st to end	Day	38% 3 21% 30% 8%	8155
August	1st to 10th	Day	27% 5% 17% 34% 16% 1	4350
	11th to 20th	Day	37% 4 13% 31% 15% 1	4169
	21st to end	Day	28% 4 16% 34% 14% 4	4311
September	1st to 10th	Day	31% 4 11% 27% 21% 6%	2400
	11th to 20th	Day	32% 4 10% 27% 23% 4	2391
	21st to end	Day	31% 5% 10% 27% 24% 4	2090
October	1st to 10th	Day	20% 2 6% 22% 39% 12%	3260
	11th to 20th	Day	23% 2 5% 22% 38% 10%	3240
	21st to end	Day	38% 2 7% 24% 26% 2	3538
November	1st to 10th	Day	34% 2 13% 25% 21% 5%	1995
	11th to 20th	Day	37% 2 10% 27% 21% 3	1827
	21st to end	Day	45% 3 9% 28% 14% 1	1680
December	1st to 10th	Day	36% 2 15% 31% 15% 1	2690
	11th to 20th	Day	44% 2 13% 28% 12% 1	3085
	21st to end	Day	67% 2 11% 13% 5%	4070
January	1st to 10th	Night	54% 2 12% 23% 9%	7933
	11th to 20th	Night	46% 2 7% 25% 16% 4	7680
	21st to end	Night	51% 2 12% 18% 15% 2	8402
February	1st to 10th	Night	49% 4 12% 21% 11% 2	2730
	11th to 20th	Night	46% 4 10% 22% 17% 2	2638
	21st to end	Night	43% 3 9% 23% 19% 4	2076
March	1st to 10th	Night	45% 2 6% 21% 22% 3	5058
	11th to 20th	Night	34% 3 6% 24% 27% 6%	5090
	21st to end	Night	50% 3 12% 24% 9% 2	5552
April	1st to 10th	Night	38% 4 10% 25% 19% 4	2100
	11th to 20th	Night	41% 4 8% 26% 16% 5%	2075
	21st to end	Night	44% 4 11% 24% 17% 2	2100
May	1st to 10th	Night	46% 3 12% 24% 14% 1	5334
	11th to 20th	Night	37% 4 11% 26% 18% 4	5029
	21st to end	Night	45% 5% 10% 20% 19% 1	5149
June	1st to 10th	Night	28% 7% 14% 31% 16% 3	1680
	11th to 20th	Night	29% 6% 11% 28% 22% 4	1680
	21st to end	Night	24% 5% 16% 30% 19% 6%	1680
July	1st to 10th	Night	32% 2 14% 29% 21% 2	4670
	11th to 20th	Night	30% 3 14% 31% 19% 3	5079
	21st to end	Night	33% 2 20% 37% 8% 1	5641
August	1st to 10th	Night	20% 4 20% 31% 23% 1	3006
	11th to 20th	Night	34% 3 12% 30% 20% 2	3039
	21st to end	Night	25% 3 15% 36% 17% 4	3586
September	1st to 10th	Night	28% 4 11% 24% 26% 7%	2000
	11th to 20th	Night	31% 5% 10% 26% 22% 5%	2005
	21st to end	Night	29% 4 8% 27% 27% 4	2290
October	1st to 10th	Night	17% 2 5% 21% 45% 9%	3920
	11th to 20th	Night	25% 2 6% 22% 31% 14%	3899
	21st to end	Night	36% 2 6% 28% 25% 2	4252
November	1st to 10th	Night	31% 4 11% 28% 20% 6%	2521
	11th to 20th	Night	36% 3 9% 26% 23% 4	2790
	21st to end	Night	44% 3 9% 25% 17% 2	2940
December	1st to 10th	Night	38% 2 11% 35% 14% 1	4720
	11th to 20th	Night	44% 2 12% 26% 15% 1	5341
	21st to end	Night	64% 2 13% 14% 6% 1	7150

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	21% 14% 37% 22% 6%	330
	11th to 20th	Day	25% 19% 42% 12% 2	330
	21st to end	Day	18% 13% 47% 17% 5%	363
February	1st to 10th	Day	22% 15% 42% 17% 5%	330
	11th to 20th	Day	24% 17% 40% 13% 6%	330
	21st to end	Day	21% 19% 40% 16% 4	273
March	1st to 10th	Day	21% 17% 40% 18% 4	330
	11th to 20th	Day	26% 16% 32% 20% 5% 1	330
	21st to end	Day	29% 19% 30% 17% 5%	373
April	1st to 10th	Day	21% 16% 30% 24% 7% 1	540
	11th to 20th	Day	20% 17% 33% 24% 6% 1	532
	21st to end	Day	21% 13% 31% 26% 8% 1	540
May	1st to 10th	Day	17% 11% 33% 29% 9% 1	732
	11th to 20th	Day	19% 9% 25% 27% 15% 4	775
	21st to end	Day	14% 7% 27% 27% 19% 6%	844
June	1st to 10th	Day	10% 3 20% 33% 26% 9%	780
	11th to 20th	Day	11% 3 22% 34% 23% 6%	780
	21st to end	Day	7% 4 28% 36% 20% 5%	780
July	1st to 10th	Day	10% 3 11% 29% 32% 15%	771
	11th to 20th	Day	7% 2 14% 35% 29% 12%	768
	21st to end	Day	9% 3 11% 35% 33% 10%	849
August	1st to 10th	Day	8% 2 15% 38% 29% 8%	776
	11th to 20th	Day	10% 2 14% 36% 30% 9%	681
	21st to end	Day	10% 1 10% 31% 34% 13%	583
September	1st to 10th	Day	11% 3 12% 31% 33% 10%	530
	11th to 20th	Day	7% 1 14% 36% 29% 13%	521
	21st to end	Day	10% 3 24% 30% 22% 10%	330
October	1st to 10th	Day	15% 5% 28% 27% 17% 8%	330
	11th to 20th	Day	15% 18% 29% 26% 9% 2	330
	21st to end	Day	26% 16% 31% 20% 6% 1	363
November	1st to 10th	Day	13% 12% 41% 23% 8% 4	330
	11th to 20th	Day	16% 17% 30% 27% 9% 2	330
	21st to end	Day	27% 13% 29% 24% 7% 1	330
December	1st to 10th	Day	17% 15% 35% 26% 6% 2	330
	11th to 20th	Day	16% 19% 34% 24% 6% 2	330
	21st to end	Day	25% 17% 36% 19% 3	363
January	1st to 10th	Night	16% 14% 39% 25% 6%	1050
	11th to 20th	Night	17% 15% 40% 23% 5%	1050
	21st to end	Night	17% 13% 41% 27% 3	1155
February	1st to 10th	Night	20% 11% 39% 25% 4	1050
	11th to 20th	Night	21% 14% 36% 27% 3	1003
	21st to end	Night	21% 13% 41% 22% 3	692
March	1st to 10th	Night	19% 13% 40% 25% 4	646
	11th to 20th	Night	21% 11% 32% 30% 5% 1	630
	21st to end	Night	24% 12% 35% 25% 4	693
April	1st to 10th	Night	15% 13% 38% 29% 5%	630
	11th to 20th	Night	19% 11% 34% 28% 8%	623
	21st to end	Night	20% 8% 33% 32% 7%	630
May	1st to 10th	Night	17% 5% 33% 36% 9%	630
	11th to 20th	Night	16% 4 25% 36% 18% 1	621
	21st to end	Night	14% 4 24% 35% 21% 2	683
June	1st to 10th	Night	8% 2 17% 45% 26% 2	630
	11th to 20th	Night	8% 2 20% 43% 25% 1	630
	21st to end	Night	4 3 21% 50% 21% 1	630
July	1st to 10th	Night	10% 2 9% 39% 37% 4	615
	11th to 20th	Night	6% 2 11% 45% 34% 3	612
	21st to end	Night	7% 1 11% 44% 35% 2	690
August	1st to 10th	Night	7% 2 10% 45% 33% 2	627
	11th to 20th	Night	6% 1 11% 45% 33% 3	606
	21st to end	Night	6% 1 9% 40% 41% 4	660
September	1st to 10th	Night	13% 1 14% 40% 30% 4	600
	11th to 20th	Night	11% 1 14% 40% 30% 4	600
	21st to end	Night	9% 4 21% 38% 24% 4	690
October	1st to 10th	Night	11% 4 23% 38% 22% 3	800
	11th to 20th	Night	17% 8% 33% 31% 11% 1	800
	21st to end	Night	21% 10% 32% 28% 9%	880
November	1st to 10th	Night	13% 8% 35% 34% 10%	820
	11th to 20th	Night	14% 10% 38% 29% 9%	900
	21st to end	Night	22% 10% 34% 27% 6%	1050
December	1st to 10th	Night	17% 10% 38% 28% 6%	1050
	11th to 20th	Night	22% 9% 33% 30% 5%	1050
	21st to end	Night	23% 13% 33% 29% 2	1155

Page generated at 2026-08-12 02:37:17. Version ac07

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