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 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	12% 8% 3 6% 4 4 4 3 5% 7% 44%	113634
	Night	13% 8% 3 7% 4 4 4 3 5% 6% 45%	114830
Transparency	Day	40% 4 12% 26% 17% 3	117279
	Night	40% 3 11% 25% 18% 3	119327
Seeing	Day	15% 9% 25% 28% 18% 5%	16152
	Night	16% 8% 29% 32% 14% 1	26159

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% 12% 4 11% 5% 4 4 3 4 6% 33%	3829
	11th to 20th	Day	9% 10% 5% 10% 4 7% 5% 3 4 5% 40%	4080
	21st to end	Day	16% 13% 5% 8% 4 3 4 3 4 4 37%	4488
February	1st to 10th	Day	17% 10% 4 10% 6% 3 4 2 5% 6% 34%	1800
	11th to 20th	Day	14% 10% 4 7% 4 4 4 3 4 5% 40%	1778
	21st to end	Day	14% 10% 4 7% 5% 3 4 3 5% 5% 40%	1651
March	1st to 10th	Day	16% 9% 3 4 3 2 3 2 3 5% 51%	4936
	11th to 20th	Day	10% 6% 2 5% 3 3 3 3 5% 7% 52%	4980
	21st to end	Day	15% 11% 4 8% 6% 4 4 4 6% 7% 33%	5497
April	1st to 10th	Day	15% 6% 3 7% 5% 3 3 3 6% 6% 43%	2400
	11th to 20th	Day	16% 9% 2 6% 4 4 5% 3 5% 6% 41%	2254
	21st to end	Day	20% 7% 2 6% 4 4 5% 4 5% 6% 35%	2280
May	1st to 10th	Day	13% 8% 3 7% 5% 4 4 5% 7% 9% 35%	4050
	11th to 20th	Day	16% 9% 3 6% 4 4 4 3 5% 7% 39%	4204
	21st to end	Day	11% 7% 2 6% 5% 5% 5% 4 5% 7% 44%	4824
June	1st to 10th	Day	7% 4 2 5% 5% 5% 5% 4 7% 10% 46%	2660
	11th to 20th	Day	8% 5% 2 6% 4 4 4 4 6% 8% 48%	2660
	21st to end	Day	6% 5% 2 5% 5% 4 5% 4 7% 10% 49%	2660
July	1st to 10th	Day	13% 6% 2 6% 4 4 4 4 6% 9% 41%	4440
	11th to 20th	Day	6% 4 2 5% 4 4 5% 4 6% 9% 51%	4198
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 5% 8% 10% 43%	4465
August	1st to 10th	Day	4 4 2 4 4 4 5% 4 8% 11% 50%	4104
	11th to 20th	Day	11% 5% 2 5% 4 5% 4 4 6% 8% 45%	3950
	21st to end	Day	6% 4 2 4 4 3 4 4 7% 9% 53%	4180
September	1st to 10th	Day	10% 5% 2 4 4 4 4 2 5% 8% 52%	2280
	11th to 20th	Day	9% 5% 2 6% 4 3 4 3 5% 8% 51%	2272
	21st to end	Day	7% 5% 2 6% 4 4 4 4 5% 7% 52%	1986
October	1st to 10th	Day	11% 4 2 6% 3 2 3 3 5% 5% 55%	1900
	11th to 20th	Day	13% 8% 2 4 3 2 3 2 3 6% 53%	1900
	21st to end	Day	16% 8% 3 6% 3 3 3 2 3 5% 47%	2090
November	1st to 10th	Day	11% 7% 2 5% 3 3 3 3 5% 5% 52%	1898
	11th to 20th	Day	14% 8% 2 6% 3 3 3 3 4 6% 49%	1740
	21st to end	Day	17% 10% 3 6% 3 3 3 2 4 5% 43%	1600
December	1st to 10th	Day	8% 9% 3 6% 4 3 4 3 4 7% 51%	2610
	11th to 20th	Day	12% 9% 4 8% 4 3 3 2 4 5% 45%	3008
	21st to end	Day	22% 18% 7% 10% 4 4 4 3 4 4 21%	3982
January	1st to 10th	Night	14% 11% 6% 14% 6% 4 3 3 3 4 33%	6118
	11th to 20th	Night	12% 9% 5% 11% 5% 6% 4 3 4 4 37%	5900
	21st to end	Night	16% 13% 4 7% 4 4 4 3 4 4 38%	6490
February	1st to 10th	Night	15% 10% 4 8% 6% 4 4 4 5% 6% 35%	2600
	11th to 20th	Night	15% 9% 4 6% 5% 3 5% 3 4 6% 40%	2508
	21st to end	Night	14% 10% 4 6% 4 3 3 2 4 5% 44%	1980
March	1st to 10th	Night	17% 11% 3 6% 3 3 3 3 4 4 45%	4947
	11th to 20th	Night	11% 6% 2 5% 3 3 3 3 4 6% 53%	4980
	21st to end	Night	15% 11% 4 8% 5% 5% 4 3 5% 6% 35%	5432
April	1st to 10th	Night	11% 7% 3 6% 4 3 3 3 4 7% 47%	2000
	11th to 20th	Night	14% 7% 2 6% 4 4 4 2 5% 7% 45%	1881
	21st to end	Night	18% 6% 3 6% 4 3 4 3 4 6% 42%	1900
May	1st to 10th	Night	15% 8% 3 6% 4 4 4 4 6% 7% 39%	2838
	11th to 20th	Night	13% 7% 3 8% 4 4 4 3 5% 9% 41%	2698
	21st to end	Night	10% 5% 2 6% 3 4 5% 3 6% 8% 49%	2743
June	1st to 10th	Night	6% 3 1 5% 4 3 4 4 6% 9% 53%	1520
	11th to 20th	Night	5% 4 2 6% 5% 4 4 4 7% 11% 49%	1520
	21st to end	Night	3 3 1 4 4 4 4 4 6% 10% 56%	1520
July	1st to 10th	Night	12% 7% 2 6% 3 3 4 3 4 9% 45%	2530
	11th to 20th	Night	3 3 1 4 3 4 3 4 6% 10% 59%	2754
	21st to end	Night	5% 4 2 6% 4 4 5% 4 7% 10% 48%	3098
August	1st to 10th	Night	4 2 1 3 3 3 5% 3 6% 9% 61%	2836
	11th to 20th	Night	11% 5% 2 5% 3 3 3 4 5% 8% 50%	2883
	21st to end	Night	4 3 1 4 3 4 4 4 6% 8% 58%	3476
September	1st to 10th	Night	10% 4 2 4 3 3 3 3 5% 6% 59%	1900
	11th to 20th	Night	9% 4 1 5% 3 4 5% 3 6% 7% 53%	1905
	21st to end	Night	7% 5% 2 5% 3 3 3 3 5% 6% 56%	2175
October	1st to 10th	Night	9% 5% 1 4 3 3 3 3 5% 6% 59%	2280
	11th to 20th	Night	15% 4 2 5% 3 3 3 2 4 5% 54%	2280
	21st to end	Night	16% 8% 2 5% 3 3 3 3 4 5% 48%	2508
November	1st to 10th	Night	11% 5% 2 4 4 3 3 3 3 6% 57%	2398
	11th to 20th	Night	11% 7% 2 6% 5% 3 3 3 4 6% 50%	2657
	21st to end	Night	16% 9% 2 5% 4 3 3 3 4 5% 46%	2800
December	1st to 10th	Night	10% 8% 3 6% 4 3 3 3 5% 6% 51%	4580
	11th to 20th	Night	16% 9% 3 6% 3 3 4 3 4 6% 43%	5199
	21st to end	Night	23% 17% 5% 9% 4 3 3 3 3 4 25%	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	54% 3 9% 21% 10% 2	3830
	11th to 20th	Day	49% 1 10% 22% 14% 4	4080
	21st to end	Day	52% 2 9% 15% 18% 3	4488
February	1st to 10th	Day	53% 3 11% 21% 11% 1	1800
	11th to 20th	Day	47% 3 12% 20% 15% 3	1787
	21st to end	Day	46% 3 8% 24% 16% 3	1651
March	1st to 10th	Day	40% 2 7% 25% 24% 3	4936
	11th to 20th	Day	33% 3 9% 24% 25% 6%	4980
	21st to end	Day	51% 3 16% 24% 5%	5499
April	1st to 10th	Day	43% 4 11% 25% 15% 2	2400
	11th to 20th	Day	44% 4 11% 25% 14% 2	2254
	21st to end	Day	49% 4 12% 22% 12% 1	2280
May	1st to 10th	Day	44% 6% 14% 23% 11% 1	4088
	11th to 20th	Day	46% 6% 11% 26% 11%	4208
	21st to end	Day	38% 6% 10% 29% 16% 1	4837
June	1st to 10th	Day	31% 6% 16% 30% 15% 1	2660
	11th to 20th	Day	32% 7% 13% 28% 17% 3	2660
	21st to end	Day	30% 6% 16% 29% 15% 4	2660
July	1st to 10th	Day	41% 4 11% 25% 16% 2	4371
	11th to 20th	Day	30% 5% 13% 33% 18% 1	4126
	21st to end	Day	35% 4 19% 29% 12% 1	4325
August	1st to 10th	Day	27% 5% 17% 34% 16% 1	4090
	11th to 20th	Day	37% 4 13% 30% 15% 1	3989
	21st to end	Day	28% 4 16% 34% 14% 4	4179
September	1st to 10th	Day	31% 5% 11% 27% 21% 6%	2280
	11th to 20th	Day	32% 4 9% 27% 24% 4	2272
	21st to end	Day	31% 5% 10% 27% 24% 4	1986
October	1st to 10th	Day	19% 2 6% 21% 39% 12%	3160
	11th to 20th	Day	22% 2 5% 22% 39% 10%	3140
	21st to end	Day	38% 2 7% 25% 27% 2	3428
November	1st to 10th	Day	35% 3 13% 23% 21% 5%	1898
	11th to 20th	Day	37% 3 10% 25% 21% 4	1740
	21st to end	Day	44% 3 9% 28% 14% 1	1600
December	1st to 10th	Day	36% 2 15% 31% 16% 1	2610
	11th to 20th	Day	44% 2 13% 28% 12% 1	3005
	21st to end	Day	68% 3 11% 13% 5%	3982
January	1st to 10th	Night	58% 2 9% 21% 9%	6118
	11th to 20th	Night	52% 2 9% 21% 13% 3	5900
	21st to end	Night	52% 2 10% 18% 16% 3	6490
February	1st to 10th	Night	50% 4 11% 20% 12% 2	2600
	11th to 20th	Night	46% 4 10% 21% 17% 2	2509
	21st to end	Night	43% 3 9% 23% 18% 4	1980
March	1st to 10th	Night	45% 2 7% 21% 22% 3	4947
	11th to 20th	Night	34% 3 6% 24% 27% 6%	4980
	21st to end	Night	50% 3 12% 24% 9% 2	5432
April	1st to 10th	Night	37% 4 10% 26% 19% 4	2000
	11th to 20th	Night	40% 4 7% 27% 17% 5%	1881
	21st to end	Night	43% 4 11% 23% 17% 2	1900
May	1st to 10th	Night	44% 5% 15% 19% 15% 1	2865
	11th to 20th	Night	41% 5% 13% 29% 11% 1	2699
	21st to end	Night	31% 7% 13% 23% 24% 2	2751
June	1st to 10th	Night	27% 7% 14% 31% 17% 4	1520
	11th to 20th	Night	28% 7% 11% 28% 22% 4	1520
	21st to end	Night	23% 5% 16% 30% 20% 6%	1520
July	1st to 10th	Night	39% 3 10% 28% 16% 3	2490
	11th to 20th	Night	23% 3 12% 39% 21% 2	2703
	21st to end	Night	31% 3 21% 32% 13% 1	2999
August	1st to 10th	Night	20% 4 20% 31% 23% 2	2826
	11th to 20th	Night	35% 3 11% 29% 20% 2	2910
	21st to end	Night	25% 3 15% 37% 16% 4	3476
September	1st to 10th	Night	27% 4 11% 24% 26% 8%	1900
	11th to 20th	Night	30% 5% 10% 26% 24% 6%	1905
	21st to end	Night	29% 4 7% 28% 26% 4	2175
October	1st to 10th	Night	17% 2 6% 21% 45% 9%	3800
	11th to 20th	Night	25% 2 5% 22% 32% 14%	3779
	21st to end	Night	36% 3 6% 28% 26% 2	4120
November	1st to 10th	Night	31% 4 12% 28% 21% 6%	2398
	11th to 20th	Night	36% 3 8% 25% 23% 5%	2657
	21st to end	Night	42% 3 10% 26% 17% 2	2800
December	1st to 10th	Night	37% 2 11% 36% 14% 1	4580
	11th to 20th	Night	44% 2 12% 26% 15% 1	5201
	21st to end	Night	64% 2 13% 14% 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	21% 14% 37% 22% 7%	300
	11th to 20th	Day	27% 17% 42% 12% 2	300
	21st to end	Day	18% 14% 45% 18% 5%	330
February	1st to 10th	Day	24% 14% 41% 16% 4	300
	11th to 20th	Day	24% 18% 39% 13% 7%	300
	21st to end	Day	20% 20% 39% 16% 4	249
March	1st to 10th	Day	18% 17% 41% 20% 4	300
	11th to 20th	Day	26% 16% 32% 21% 5% 1	300
	21st to end	Day	31% 19% 29% 17% 5%	340
April	1st to 10th	Day	20% 17% 30% 24% 8% 1	500
	11th to 20th	Day	20% 15% 32% 26% 7% 1	452
	21st to end	Day	22% 13% 29% 26% 8% 1	460
May	1st to 10th	Day	17% 11% 32% 29% 9% 1	634
	11th to 20th	Day	20% 9% 22% 29% 16% 4	675
	21st to end	Day	13% 7% 28% 26% 20% 6%	734
June	1st to 10th	Day	8% 3 19% 35% 27% 10%	680
	11th to 20th	Day	10% 2 22% 36% 24% 6%	680
	21st to end	Day	5% 5% 29% 36% 19% 6%	680
July	1st to 10th	Day	11% 3 12% 27% 33% 14%	671
	11th to 20th	Day	6% 2 15% 36% 29% 12%	668
	21st to end	Day	8% 4 10% 34% 34% 10%	739
August	1st to 10th	Day	7% 3 14% 38% 30% 8%	676
	11th to 20th	Day	10% 2 14% 36% 29% 9%	613
	21st to end	Day	11% 1 10% 31% 35% 13%	539
September	1st to 10th	Day	11% 3 12% 30% 33% 11%	490
	11th to 20th	Day	7% 1 15% 37% 28% 12%	482
	21st to end	Day	9% 3 26% 31% 21% 9%	300
October	1st to 10th	Day	15% 6% 29% 25% 17% 8%	300
	11th to 20th	Day	14% 18% 31% 26% 9% 2	300
	21st to end	Day	24% 17% 31% 21% 7% 1	330
November	1st to 10th	Day	14% 11% 39% 23% 8% 4	300
	11th to 20th	Day	17% 17% 30% 26% 9% 2	300
	21st to end	Day	26% 13% 31% 24% 6% 1	300
December	1st to 10th	Day	16% 14% 36% 26% 6% 2	300
	11th to 20th	Day	16% 20% 33% 24% 6% 1	300
	21st to end	Day	26% 18% 36% 18% 2	330
January	1st to 10th	Night	16% 14% 39% 24% 7%	1000
	11th to 20th	Night	18% 14% 39% 24% 5% 1	1000
	21st to end	Night	17% 12% 41% 27% 3	1100
February	1st to 10th	Night	21% 11% 39% 25% 4	1000
	11th to 20th	Night	21% 14% 36% 26% 3	954
	21st to end	Night	21% 13% 41% 21% 3	660
March	1st to 10th	Night	18% 13% 40% 26% 4	615
	11th to 20th	Night	21% 11% 32% 31% 5% 1	600
	21st to end	Night	24% 12% 34% 25% 4	660
April	1st to 10th	Night	15% 13% 38% 29% 5%	600
	11th to 20th	Night	19% 11% 32% 29% 9%	565
	21st to end	Night	19% 8% 34% 31% 7%	570
May	1st to 10th	Night	17% 6% 32% 36% 9% 1	570
	11th to 20th	Night	17% 3 24% 38% 18% 1	561
	21st to end	Night	14% 4 24% 34% 22% 2	617
June	1st to 10th	Night	7% 2 16% 45% 27% 3	570
	11th to 20th	Night	7% 2 21% 44% 26% 1	570
	21st to end	Night	4 3 21% 51% 21% 1	570
July	1st to 10th	Night	11% 2 9% 38% 36% 4	555
	11th to 20th	Night	5% 2 12% 46% 33% 2	552
	21st to end	Night	7% 2 12% 43% 35% 2	624
August	1st to 10th	Night	7% 2 9% 44% 35% 2	567
	11th to 20th	Night	7% 2 11% 46% 32% 3	564
	21st to end	Night	6% 1 9% 39% 41% 4	627
September	1st to 10th	Night	12% 1 14% 39% 30% 4	570
	11th to 20th	Night	11% 1 15% 40% 28% 4	570
	21st to end	Night	9% 4 22% 38% 23% 4	655
October	1st to 10th	Night	11% 4 23% 36% 22% 3	760
	11th to 20th	Night	17% 8% 34% 31% 10% 1	760
	21st to end	Night	20% 10% 31% 28% 10%	836
November	1st to 10th	Night	13% 8% 34% 34% 11%	780
	11th to 20th	Night	15% 11% 37% 29% 9%	857
	21st to end	Night	21% 10% 35% 27% 7%	1000
December	1st to 10th	Night	17% 11% 38% 28% 6% 1	1000
	11th to 20th	Night	23% 9% 32% 31% 6%	1000
	21st to end	Night	23% 13% 33% 29% 2	1100

Page generated at 2025-04-08 08:17:25. Version ac07

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