Jefferson City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jefferson City clear sky chart from 2005-11-06 to 2026-10-29.

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 4 5% 7% 43%	149493
	Night	12% 8% 3 7% 4 4 4 3 5% 7% 45%	142939
Transparency	Day	38% 6% 12% 25% 17% 3	153092
	Night	39% 5% 11% 25% 17% 3	147419
Seeing	Day	17% 12% 28% 26% 14% 3	18370
	Night	17% 12% 29% 29% 12% 1	28100

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% 12% 5% 10% 4 4 4 3 4 5% 36%	4908
	11th to 20th	Day	7% 9% 3 8% 5% 6% 5% 3 4 7% 43%	5310
	21st to end	Day	16% 11% 5% 7% 4 3 3 3 3 5% 39%	5812
February	1st to 10th	Day	15% 12% 4 9% 5% 4 3 3 5% 5% 34%	1890
	11th to 20th	Day	16% 11% 3 6% 4 3 4 3 4 5% 40%	1914
	21st to end	Day	15% 9% 4 6% 4 4 4 4 5% 5% 40%	1730
March	1st to 10th	Day	16% 9% 2 5% 3 3 3 2 3 4 49%	4972
	11th to 20th	Day	10% 6% 2 5% 4 3 4 3 5% 6% 53%	5090
	21st to end	Day	14% 10% 3 9% 5% 5% 5% 4 6% 7% 34%	5673
April	1st to 10th	Day	14% 7% 3 6% 5% 4 4 4 4 6% 43%	2520
	11th to 20th	Day	16% 8% 3 6% 4 4 4 4 4 6% 42%	2494
	21st to end	Day	18% 9% 3 7% 4 4 4 4 5% 7% 35%	2520
May	1st to 10th	Day	15% 7% 3 7% 5% 4 5% 4 7% 9% 36%	7375
	11th to 20th	Day	13% 8% 3 8% 4 4 5% 4 5% 7% 39%	7956
	21st to end	Day	18% 8% 3 7% 5% 4 5% 4 5% 7% 34%	9047
June	1st to 10th	Day	8% 5% 2 5% 5% 4 5% 4 8% 9% 44%	2940
	11th to 20th	Day	8% 5% 2 5% 4 4 4 5% 7% 10% 47%	2940
	21st to end	Day	7% 3 1 5% 4 4 5% 4 7% 9% 48%	2940
July	1st to 10th	Day	9% 6% 2 6% 4 4 4 4 6% 10% 45%	8280
	11th to 20th	Day	6% 5% 2 6% 5% 5% 5% 4 7% 10% 44%	7929
	21st to end	Day	7% 5% 2 5% 4 5% 5% 5% 8% 12% 41%	8337
August	1st to 10th	Day	7% 4 2 5% 4 4 4 4 7% 10% 49%	6014
	11th to 20th	Day	9% 5% 2 6% 4 4 4 4 7% 10% 45%	5715
	21st to end	Day	4 4 2 5% 4 4 4 3 6% 9% 55%	6080
September	1st to 10th	Day	11% 4 2 5% 4 4 4 4 5% 7% 51%	2520
	11th to 20th	Day	9% 5% 2 5% 4 4 4 3 5% 7% 51%	2520
	21st to end	Day	8% 6% 2 5% 4 3 4 4 5% 6% 52%	2207
October	1st to 10th	Day	10% 5% 2 5% 3 3 4 3 5% 5% 56%	2100
	11th to 20th	Day	15% 6% 2 5% 3 3 3 2 3 5% 54%	2100
	21st to end	Day	18% 8% 2 6% 3 3 2 2 4 5% 47%	2280
November	1st to 10th	Day	12% 6% 2 4 3 3 3 2 5% 6% 53%	1963
	11th to 20th	Day	14% 8% 3 5% 3 4 3 3 5% 6% 47%	1889
	21st to end	Day	17% 9% 3 6% 3 3 3 3 4 6% 43%	1680
December	1st to 10th	Day	10% 9% 3 7% 4 3 3 2 4 5% 50%	2690
	11th to 20th	Day	11% 8% 4 8% 5% 4 3 2 4 5% 45%	3088
	21st to end	Day	22% 20% 5% 10% 4 4 3 3 4 4 23%	4070
January	1st to 10th	Night	13% 11% 6% 11% 5% 4 4 3 3 4 37%	8010
	11th to 20th	Night	9% 8% 4 11% 6% 5% 4 3 4 4 41%	7680
	21st to end	Night	15% 12% 4 7% 5% 4 4 3 4 5% 38%	8402
February	1st to 10th	Night	14% 11% 4 8% 5% 3 4 4 5% 6% 37%	2730
	11th to 20th	Night	15% 8% 3 8% 4 5% 4 3 4 6% 41%	2590
	21st to end	Night	15% 10% 3 6% 4 3 3 3 4 5% 43%	2076
March	1st to 10th	Night	18% 11% 3 5% 3 3 3 3 4 5% 44%	5131
	11th to 20th	Night	12% 7% 2 5% 3 3 3 3 4 7% 51%	5090
	21st to end	Night	14% 10% 4 8% 5% 5% 4 4 5% 6% 35%	5497
April	1st to 10th	Night	12% 7% 2 7% 4 3 4 3 4 7% 47%	2100
	11th to 20th	Night	13% 8% 3 6% 3 3 4 3 4 8% 45%	2075
	21st to end	Night	16% 9% 2 6% 4 3 4 3 5% 7% 41%	2100
May	1st to 10th	Night	15% 9% 3 6% 5% 4 4 4 5% 7% 37%	5492
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 6% 9% 44%	4932
	21st to end	Night	16% 8% 3 7% 5% 4 4 4 6% 8% 35%	5139
June	1st to 10th	Night	9% 4 2 5% 3 4 4 4 6% 8% 51%	1680
	11th to 20th	Night	6% 5% 1 5% 4 4 5% 3 6% 11% 50%	1680
	21st to end	Night	4 3 1 3 3 3 4 3 7% 11% 57%	1680
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 6% 10% 49%	4708
	11th to 20th	Night	5% 4 2 5% 4 4 5% 4 7% 10% 50%	5040
	21st to end	Night	5% 4 2 5% 4 5% 5% 4 7% 11% 48%	5770
August	1st to 10th	Night	7% 4 1 4 3 3 4 3 5% 8% 58%	4156
	11th to 20th	Night	9% 5% 2 5% 4 3 4 3 5% 9% 51%	4339
	21st to end	Night	5% 3 1 4 3 3 4 3 6% 9% 61%	5046
September	1st to 10th	Night	10% 4 2 4 4 3 4 3 4 7% 55%	2100
	11th to 20th	Night	8% 5% 2 5% 4 5% 4 4 7% 7% 50%	2100
	21st to end	Night	9% 5% 2 5% 4 4 4 3 4 7% 53%	2387
October	1st to 10th	Night	8% 3 2 4 3 3 3 3 5% 6% 61%	2520
	11th to 20th	Night	13% 6% 2 5% 3 3 3 3 4 5% 52%	2520
	21st to end	Night	17% 8% 2 5% 3 3 3 3 4 4 49%	2737
November	1st to 10th	Night	11% 7% 2 4 3 3 3 3 4 5% 56%	2554
	11th to 20th	Night	12% 7% 3 6% 4 3 3 2 4 6% 50%	2730
	21st to end	Night	17% 9% 3 7% 3 3 3 3 4 5% 45%	2939
December	1st to 10th	Night	10% 9% 3 6% 4 4 4 3 5% 5% 48%	4720
	11th to 20th	Night	16% 9% 4 6% 4 3 3 3 4 5% 43%	5339
	21st to end	Night	24% 18% 5% 9% 4 4 3 2 3 4 25%	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	51% 4 10% 23% 11% 1	4909
	11th to 20th	Day	41% 4 11% 25% 15% 4	5310
	21st to end	Day	49% 3 10% 17% 17% 4	5812
February	1st to 10th	Day	53% 4 10% 21% 11% 1	1890
	11th to 20th	Day	46% 5% 10% 20% 15% 4	1923
	21st to end	Day	45% 4 8% 24% 15% 4	1730
March	1st to 10th	Day	40% 3 6% 23% 23% 5%	4972
	11th to 20th	Day	32% 4 8% 24% 25% 6%	5090
	21st to end	Day	48% 6% 13% 25% 7%	5675
April	1st to 10th	Day	41% 6% 11% 24% 17% 2	2520
	11th to 20th	Day	43% 6% 10% 24% 15% 3	2494
	21st to end	Day	49% 5% 11% 22% 12% 1	2520
May	1st to 10th	Day	43% 8% 13% 23% 13% 1	7410
	11th to 20th	Day	43% 7% 9% 23% 15% 2	7960
	21st to end	Day	48% 6% 9% 22% 14% 1	9061
June	1st to 10th	Day	32% 9% 15% 26% 16% 1	2940
	11th to 20th	Day	30% 8% 13% 28% 17% 4	2940
	21st to end	Day	29% 8% 16% 27% 15% 4	2940
July	1st to 10th	Day	33% 7% 14% 26% 19% 1	8211
	11th to 20th	Day	32% 9% 15% 26% 15% 2	7855
	21st to end	Day	31% 9% 22% 30% 7% 1	8155
August	1st to 10th	Day	29% 8% 15% 31% 17%	6000
	11th to 20th	Day	34% 7% 15% 31% 12% 1	5754
	21st to end	Day	25% 6% 14% 37% 16% 3	6079
September	1st to 10th	Day	32% 6% 11% 26% 21% 5%	2520
	11th to 20th	Day	32% 5% 9% 28% 22% 3	2520
	21st to end	Day	32% 6% 8% 25% 24% 3	2207
October	1st to 10th	Day	19% 3 5% 18% 44% 11%	3360
	11th to 20th	Day	23% 2 5% 22% 37% 10%	3340
	21st to end	Day	34% 3 7% 26% 26% 2	3618
November	1st to 10th	Day	32% 4 13% 25% 22% 5%	1963
	11th to 20th	Day	38% 3 8% 25% 21% 4	1889
	21st to end	Day	44% 4 9% 28% 15% 1	1680
December	1st to 10th	Day	38% 3 10% 33% 15% 1	2690
	11th to 20th	Day	42% 4 12% 27% 14% 1	3085
	21st to end	Day	66% 4 11% 12% 6%	4070
January	1st to 10th	Night	52% 4 11% 24% 9%	8011
	11th to 20th	Night	47% 4 7% 24% 15% 3	7680
	21st to end	Night	50% 3 12% 19% 14% 2	8402
February	1st to 10th	Night	49% 5% 11% 21% 13% 2	2730
	11th to 20th	Night	45% 4 11% 21% 16% 3	2591
	21st to end	Night	43% 4 9% 23% 17% 4	2076
March	1st to 10th	Night	44% 4 7% 21% 21% 3	5131
	11th to 20th	Night	34% 4 8% 23% 25% 6%	5090
	21st to end	Night	48% 7% 11% 22% 10% 1	5497
April	1st to 10th	Night	37% 5% 11% 25% 18% 4	2100
	11th to 20th	Night	39% 6% 10% 23% 16% 6%	2075
	21st to end	Night	43% 5% 10% 24% 17% 1	2100
May	1st to 10th	Night	44% 8% 13% 22% 13% 1	5522
	11th to 20th	Night	36% 7% 11% 24% 18% 4	4933
	21st to end	Night	46% 8% 11% 19% 15% 1	5149
June	1st to 10th	Night	30% 7% 14% 29% 16% 3	1680
	11th to 20th	Night	28% 7% 10% 28% 24% 3	1680
	21st to end	Night	21% 7% 17% 29% 20% 6%	1680
July	1st to 10th	Night	30% 6% 14% 27% 21% 1	4670
	11th to 20th	Night	26% 9% 15% 30% 17% 2	4994
	21st to end	Night	28% 8% 20% 34% 9%	5641
August	1st to 10th	Night	24% 6% 18% 30% 22% 1	4146
	11th to 20th	Night	31% 6% 14% 32% 15% 2	4366
	21st to end	Night	20% 6% 16% 38% 17% 3	5046
September	1st to 10th	Night	30% 4 10% 24% 25% 6%	2100
	11th to 20th	Night	30% 7% 11% 25% 23% 5%	2100
	21st to end	Night	31% 5% 8% 26% 26% 4	2387
October	1st to 10th	Night	15% 3 5% 22% 45% 9%	4040
	11th to 20th	Night	24% 3 6% 21% 33% 13%	4019
	21st to end	Night	34% 3 7% 28% 25% 3	4349
November	1st to 10th	Night	31% 4 11% 29% 19% 6%	2554
	11th to 20th	Night	36% 3 8% 26% 22% 4	2730
	21st to end	Night	43% 4 9% 26% 16% 2	2939
December	1st to 10th	Night	38% 4 10% 33% 13% 1	4720
	11th to 20th	Night	44% 4 11% 24% 16% 1	5341
	21st to end	Night	65% 4 12% 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	26% 21% 36% 14% 3	330
	11th to 20th	Day	31% 21% 37% 9% 1	330
	21st to end	Day	21% 25% 39% 12% 3	363
February	1st to 10th	Day	27% 23% 35% 14% 2	330
	11th to 20th	Day	33% 21% 32% 12% 3	330
	21st to end	Day	31% 23% 33% 10% 3	273
March	1st to 10th	Day	21% 30% 37% 11% 1	330
	11th to 20th	Day	32% 19% 35% 12% 2	330
	21st to end	Day	34% 24% 31% 11% 1	402
April	1st to 10th	Day	25% 17% 35% 17% 5% 1	540
	11th to 20th	Day	30% 17% 32% 16% 5%	532
	21st to end	Day	26% 15% 35% 19% 5%	540
May	1st to 10th	Day	20% 16% 37% 21% 6%	664
	11th to 20th	Day	19% 15% 29% 23% 12% 2	775
	21st to end	Day	16% 11% 34% 22% 14% 4	844
June	1st to 10th	Day	10% 5% 29% 33% 17% 5%	780
	11th to 20th	Day	7% 6% 27% 40% 18% 2	780
	21st to end	Day	7% 9% 33% 36% 13% 3	780
July	1st to 10th	Day	11% 3 17% 32% 28% 9%	771
	11th to 20th	Day	6% 4 23% 37% 26% 5%	768
	21st to end	Day	9% 4 17% 36% 27% 6%	849
August	1st to 10th	Day	8% 2 20% 42% 22% 6%	776
	11th to 20th	Day	9% 4 20% 36% 26% 5%	662
	21st to end	Day	9% 3 18% 32% 30% 8%	627
September	1st to 10th	Day	12% 4 16% 33% 29% 6%	570
	11th to 20th	Day	7% 4 18% 34% 27% 10%	570
	21st to end	Day	12% 10% 23% 33% 17% 5%	404
October	1st to 10th	Day	12% 6% 33% 31% 14% 4	360
	11th to 20th	Day	19% 20% 32% 18% 9% 2	360
	21st to end	Day	32% 18% 29% 16% 3 1	387
November	1st to 10th	Day	16% 17% 39% 19% 7% 2	330
	11th to 20th	Day	25% 18% 31% 19% 6% 2	330
	21st to end	Day	30% 16% 27% 22% 4 1	330
December	1st to 10th	Day	21% 22% 35% 14% 6% 2	330
	11th to 20th	Day	23% 21% 38% 15% 4 1	330
	21st to end	Day	30% 24% 33% 11% 2	363
January	1st to 10th	Night	20% 18% 36% 22% 4	1050
	11th to 20th	Night	23% 21% 35% 18% 4	1050
	21st to end	Night	20% 18% 37% 22% 2	1155
February	1st to 10th	Night	22% 17% 38% 20% 3	1050
	11th to 20th	Night	23% 19% 34% 22% 2	956
	21st to end	Night	25% 19% 36% 18% 2	692
March	1st to 10th	Night	24% 17% 37% 19% 3	684
	11th to 20th	Night	24% 14% 34% 25% 3	630
	21st to end	Night	27% 18% 32% 19% 3	693
April	1st to 10th	Night	18% 17% 36% 24% 4	630
	11th to 20th	Night	21% 14% 36% 24% 5%	623
	21st to end	Night	20% 13% 37% 24% 6%	630
May	1st to 10th	Night	18% 8% 35% 32% 7%	630
	11th to 20th	Night	16% 8% 31% 31% 14% 1	621
	21st to end	Night	13% 7% 29% 31% 18% 1	683
June	1st to 10th	Night	11% 4 20% 40% 24% 2	630
	11th to 20th	Night	7% 3 26% 43% 19% 1	630
	21st to end	Night	4 3 28% 45% 18% 2	630
July	1st to 10th	Night	11% 1 13% 36% 33% 5%	615
	11th to 20th	Night	4 2 17% 42% 31% 3	612
	21st to end	Night	6% 2 17% 40% 32% 3	690
August	1st to 10th	Night	7% 2 14% 43% 31% 1	627
	11th to 20th	Night	8% 3 13% 42% 32% 2	624
	21st to end	Night	6% 3 14% 39% 35% 3	693
September	1st to 10th	Night	12% 3 16% 39% 26% 4	630
	11th to 20th	Night	10% 3 17% 37% 29% 5%	630
	21st to end	Night	10% 6% 22% 36% 22% 4	755
October	1st to 10th	Night	10% 6% 25% 34% 22% 3	840
	11th to 20th	Night	16% 12% 32% 29% 10%	840
	21st to end	Night	23% 12% 32% 25% 7%	913
November	1st to 10th	Night	15% 12% 36% 29% 9%	820
	11th to 20th	Night	17% 16% 33% 26% 7%	840
	21st to end	Night	24% 14% 32% 24% 6%	1049
December	1st to 10th	Night	21% 15% 34% 24% 4	1050
	11th to 20th	Night	25% 14% 32% 25% 4	1050
	21st to end	Night	27% 17% 32% 22% 2	1155

Page generated at 2026-10-26 03:37:48. Version ac07

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