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 2025-07-06.

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% 43%	120030
	Night	13% 8% 3 7% 4 4 4 3 4 6% 44%	118994
Transparency	Day	39% 6% 11% 25% 17% 3	123671
	Night	40% 5% 11% 24% 18% 3	123496
Seeing	Day	18% 12% 29% 25% 13% 3	16531
	Night	18% 12% 30% 28% 12% 1	26377

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 10% 4 4 4 3 5% 5% 34%	3778
	11th to 20th	Day	9% 11% 4 8% 5% 6% 4 3 4 6% 40%	4080
	21st to end	Day	17% 12% 5% 7% 3 3 4 4 4 5% 37%	4488
February	1st to 10th	Day	16% 12% 5% 9% 5% 4 3 3 5% 5% 33%	1800
	11th to 20th	Day	16% 12% 3 6% 4 3 4 3 4 6% 40%	1820
	21st to end	Day	16% 9% 4 6% 4 4 4 4 5% 5% 40%	1650
March	1st to 10th	Day	16% 9% 2 5% 3 3 3 2 3 4 50%	4864
	11th to 20th	Day	10% 5% 2 5% 4 3 4 3 5% 6% 53%	4980
	21st to end	Day	14% 10% 3 9% 5% 5% 5% 4 6% 7% 33%	5550
April	1st to 10th	Day	14% 7% 3 6% 5% 4 3 4 4 6% 44%	2400
	11th to 20th	Day	17% 8% 2 5% 4 4 4 4 4 6% 42%	2374
	21st to end	Day	19% 9% 3 7% 4 4 4 4 5% 6% 34%	2400
May	1st to 10th	Day	15% 8% 3 8% 5% 4 4 4 7% 9% 33%	5676
	11th to 20th	Day	14% 7% 3 7% 5% 4 5% 4 6% 8% 38%	6121
	21st to end	Day	17% 6% 2 6% 5% 4 4 3 5% 6% 40%	6935
June	1st to 10th	Day	8% 5% 2 5% 5% 4 5% 4 8% 9% 45%	2800
	11th to 20th	Day	8% 5% 2 5% 4 4 4 5% 6% 10% 47%	2800
	21st to end	Day	6% 3 1 5% 4 4 5% 4 7% 10% 49%	2800
July	1st to 10th	Day	13% 7% 2 6% 5% 3 4 4 6% 9% 42%	4511
	11th to 20th	Day	4 5% 2 6% 5% 4 5% 3 7% 10% 49%	4257
	21st to end	Day	6% 5% 2 6% 5% 5% 5% 6% 8% 12% 40%	4465
August	1st to 10th	Day	5% 4 2 5% 4 4 4 4 8% 11% 51%	4104
	11th to 20th	Day	12% 5% 2 6% 4 4 4 3 6% 8% 45%	3883
	21st to end	Day	6% 5% 2 5% 4 4 4 4 6% 8% 53%	4180
September	1st to 10th	Day	11% 4 2 5% 4 4 4 4 5% 7% 50%	2280
	11th to 20th	Day	10% 6% 2 5% 4 4 4 3 5% 6% 52%	2280
	21st to end	Day	7% 6% 2 5% 4 3 4 4 5% 7% 53%	1997
October	1st to 10th	Day	10% 5% 2 5% 3 3 4 3 5% 5% 55%	1900
	11th to 20th	Day	15% 6% 2 5% 3 3 2 2 3 5% 53%	1900
	21st to end	Day	18% 7% 2 6% 3 3 2 2 4 5% 47%	2090
November	1st to 10th	Day	12% 7% 2 4 3 3 3 2 5% 6% 53%	1868
	11th to 20th	Day	14% 8% 2 5% 3 4 3 2 4 6% 47%	1799
	21st to end	Day	17% 9% 3 5% 3 3 3 3 4 7% 43%	1600
December	1st to 10th	Day	9% 9% 3 7% 4 3 3 2 4 5% 51%	2610
	11th to 20th	Day	11% 8% 4 8% 5% 4 4 2 4 5% 45%	3008
	21st to end	Day	22% 20% 5% 10% 4 4 3 2 4 4 22%	3982
January	1st to 10th	Night	15% 11% 7% 12% 6% 4 4 3 3 4 31%	6182
	11th to 20th	Night	11% 9% 5% 13% 6% 6% 4 3 3 4 36%	5900
	21st to end	Night	17% 12% 4 7% 4 3 3 3 3 5% 39%	6490
February	1st to 10th	Night	14% 11% 4 8% 5% 3 4 4 5% 5% 35%	2600
	11th to 20th	Night	15% 8% 3 8% 4 5% 4 3 4 5% 40%	2464
	21st to end	Night	15% 9% 3 7% 4 3 3 3 4 5% 43%	1980
March	1st to 10th	Night	18% 11% 3 5% 3 3 3 3 4 5% 44%	5018
	11th to 20th	Night	12% 7% 2 5% 3 3 3 3 4 7% 51%	4980
	21st to end	Night	15% 10% 4 8% 5% 5% 4 4 5% 6% 35%	5378
April	1st to 10th	Night	12% 7% 2 6% 4 3 3 3 4 7% 48%	2000
	11th to 20th	Night	13% 8% 3 6% 3 3 4 3 4 8% 46%	1975
	21st to end	Night	16% 9% 2 6% 4 3 4 3 5% 7% 40%	2000
May	1st to 10th	Night	16% 9% 3 6% 4 4 4 4 5% 7% 37%	4227
	11th to 20th	Night	12% 7% 2 7% 4 4 3 3 6% 9% 42%	3790
	21st to end	Night	15% 7% 2 6% 4 3 4 3 5% 8% 41%	3942
June	1st to 10th	Night	9% 3 2 5% 3 4 4 4 7% 8% 51%	1600
	11th to 20th	Night	6% 5% 1 5% 4 4 4 3 6% 11% 51%	1600
	21st to end	Night	3 3 1 3 3 3 4 3 7% 11% 58%	1600
July	1st to 10th	Night	11% 6% 2 6% 3 4 4 4 5% 9% 46%	2570
	11th to 20th	Night	4 3 2 4 3 4 4 3 6% 10% 57%	2709
	21st to end	Night	5% 5% 2 6% 4 5% 4 4 6% 10% 48%	3098
August	1st to 10th	Night	4 3 1 4 3 2 3 3 5% 9% 63%	2836
	11th to 20th	Night	11% 6% 2 5% 4 3 4 3 5% 7% 51%	2949
	21st to end	Night	5% 3 1 4 3 3 4 3 6% 9% 58%	3476
September	1st to 10th	Night	11% 4 2 4 3 3 4 3 4 7% 57%	1900
	11th to 20th	Night	9% 5% 2 5% 3 4 4 4 6% 7% 52%	1900
	21st to end	Night	8% 5% 1 5% 4 4 4 3 4 7% 55%	2159
October	1st to 10th	Night	8% 4 2 4 3 3 3 3 5% 6% 60%	2280
	11th to 20th	Night	13% 6% 2 4 3 3 3 3 4 5% 53%	2280
	21st to end	Night	17% 8% 2 5% 3 3 3 3 3 4 50%	2508
November	1st to 10th	Night	11% 7% 2 4 3 3 3 2 4 5% 57%	2429
	11th to 20th	Night	13% 7% 3 6% 4 3 3 2 4 6% 50%	2600
	21st to end	Night	16% 9% 3 6% 3 3 3 3 4 5% 46%	2799
December	1st to 10th	Night	10% 8% 3 5% 4 4 4 3 5% 5% 48%	4580
	11th to 20th	Night	16% 9% 4 6% 4 3 3 3 4 5% 42%	5199
	21st to end	Night	24% 18% 5% 9% 4 4 3 2 3 4 24%	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	53% 5% 10% 20% 11% 1	3779
	11th to 20th	Day	45% 4 11% 22% 15% 4	4080
	21st to end	Day	49% 4 9% 16% 18% 4	4488
February	1st to 10th	Day	54% 4 9% 20% 12% 1	1800
	11th to 20th	Day	47% 5% 10% 20% 15% 4	1829
	21st to end	Day	45% 5% 8% 23% 15% 4	1650
March	1st to 10th	Day	40% 3 6% 23% 24% 5%	4864
	11th to 20th	Day	32% 4 8% 24% 25% 6%	4980
	21st to end	Day	49% 6% 13% 25% 7%	5552
April	1st to 10th	Day	40% 5% 11% 24% 17% 2	2400
	11th to 20th	Day	42% 6% 10% 24% 15% 2	2374
	21st to end	Day	50% 5% 11% 21% 13% 1	2400
May	1st to 10th	Day	44% 8% 13% 21% 13%	5711
	11th to 20th	Day	42% 8% 10% 24% 13% 3	6125
	21st to end	Day	43% 6% 9% 25% 16% 1	6949
June	1st to 10th	Day	32% 9% 15% 27% 16% 1	2800
	11th to 20th	Day	30% 8% 13% 28% 17% 3	2800
	21st to end	Day	28% 8% 16% 28% 16% 4	2800
July	1st to 10th	Day	38% 7% 12% 25% 16% 2	4442
	11th to 20th	Day	28% 8% 14% 32% 16% 2	4183
	21st to end	Day	32% 10% 20% 28% 9% 1	4325
August	1st to 10th	Day	25% 8% 17% 35% 15% 1	4090
	11th to 20th	Day	37% 7% 13% 27% 16% 1	3922
	21st to end	Day	27% 7% 15% 34% 14% 4	4179
September	1st to 10th	Day	33% 6% 11% 25% 21% 5%	2280
	11th to 20th	Day	32% 5% 9% 27% 24% 3	2280
	21st to end	Day	30% 6% 9% 27% 24% 4	1997
October	1st to 10th	Day	19% 3 5% 18% 44% 11%	3160
	11th to 20th	Day	23% 2 5% 23% 37% 11%	3140
	21st to end	Day	34% 3 7% 26% 27% 2	3428
November	1st to 10th	Day	32% 4 13% 23% 22% 5%	1868
	11th to 20th	Day	39% 3 8% 24% 22% 5%	1799
	21st to end	Day	43% 4 9% 29% 15% 1	1600
December	1st to 10th	Day	37% 3 10% 33% 15% 1	2610
	11th to 20th	Day	42% 4 12% 26% 15% 1	3005
	21st to end	Day	67% 4 11% 12% 6%	3982
January	1st to 10th	Night	57% 4 8% 21% 9% 1	6182
	11th to 20th	Night	54% 4 8% 21% 12% 2	5900
	21st to end	Night	50% 3 10% 19% 15% 3	6490
February	1st to 10th	Night	50% 5% 10% 20% 13% 2	2600
	11th to 20th	Night	46% 4 11% 20% 16% 3	2465
	21st to end	Night	44% 4 9% 22% 17% 4	1980
March	1st to 10th	Night	44% 4 7% 21% 21% 3	5018
	11th to 20th	Night	34% 4 8% 23% 25% 6%	4980
	21st to end	Night	49% 7% 12% 22% 9% 1	5378
April	1st to 10th	Night	36% 5% 11% 26% 19% 4	2000
	11th to 20th	Night	38% 5% 10% 24% 17% 6%	1975
	21st to end	Night	43% 5% 10% 24% 16% 1	2000
May	1st to 10th	Night	44% 8% 14% 19% 13% 1	4257
	11th to 20th	Night	38% 8% 11% 23% 15% 5%	3791
	21st to end	Night	39% 8% 11% 23% 17% 1	3950
June	1st to 10th	Night	30% 8% 14% 30% 16% 3	1600
	11th to 20th	Night	27% 7% 10% 28% 24% 4	1600
	21st to end	Night	20% 6% 18% 29% 21% 7%	1600
July	1st to 10th	Night	36% 6% 10% 28% 17% 2	2530
	11th to 20th	Night	21% 7% 12% 39% 19% 2	2660
	21st to end	Night	29% 9% 19% 30% 13% 1	2999
August	1st to 10th	Night	19% 5% 21% 31% 22% 2	2826
	11th to 20th	Night	33% 6% 12% 28% 18% 3	2976
	21st to end	Night	22% 6% 17% 36% 15% 4	3476
September	1st to 10th	Night	29% 5% 11% 24% 25% 7%	1900
	11th to 20th	Night	29% 7% 10% 24% 24% 5%	1900
	21st to end	Night	30% 5% 8% 27% 27% 3	2159
October	1st to 10th	Night	15% 3 5% 22% 45% 9%	3800
	11th to 20th	Night	23% 3 6% 21% 33% 14%	3779
	21st to end	Night	34% 3 7% 27% 26% 3	4120
November	1st to 10th	Night	31% 4 11% 28% 19% 6%	2429
	11th to 20th	Night	37% 3 7% 25% 23% 4	2600
	21st to end	Night	42% 4 10% 26% 17% 2	2799
December	1st to 10th	Night	37% 4 10% 34% 14% 1	4580
	11th to 20th	Night	45% 4 11% 24% 16% 1	5201
	21st to end	Night	65% 4 12% 13% 5% 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	26% 21% 36% 14% 3	300
	11th to 20th	Day	33% 19% 37% 9% 1	300
	21st to end	Day	22% 25% 38% 13% 3	330
February	1st to 10th	Day	29% 22% 34% 12% 2	300
	11th to 20th	Day	34% 21% 30% 12% 3	300
	21st to end	Day	31% 23% 34% 10% 2	249
March	1st to 10th	Day	21% 30% 37% 11% 1	300
	11th to 20th	Day	32% 20% 33% 13% 2	300
	21st to end	Day	36% 23% 29% 11% 1	367
April	1st to 10th	Day	25% 17% 35% 17% 5% 1	500
	11th to 20th	Day	30% 17% 32% 16% 5%	492
	21st to end	Day	27% 15% 34% 19% 5%	500
May	1st to 10th	Day	20% 16% 37% 21% 6%	618
	11th to 20th	Day	19% 15% 28% 24% 12% 2	725
	21st to end	Day	16% 11% 34% 22% 14% 4	789
June	1st to 10th	Day	10% 5% 28% 34% 17% 5%	730
	11th to 20th	Day	7% 5% 27% 41% 18% 2	730
	21st to end	Day	6% 9% 33% 36% 13% 4	730
July	1st to 10th	Day	12% 2 18% 31% 28% 9%	697
	11th to 20th	Day	6% 4 24% 36% 26% 4	668
	21st to end	Day	9% 4 18% 36% 27% 6%	739
August	1st to 10th	Day	8% 2 20% 41% 23% 5%	676
	11th to 20th	Day	10% 4 22% 35% 24% 5%	572
	21st to end	Day	9% 3 17% 31% 30% 9%	539
September	1st to 10th	Day	13% 4 16% 32% 28% 7%	490
	11th to 20th	Day	8% 4 20% 34% 25% 9%	490
	21st to end	Day	11% 11% 25% 35% 15% 3	340
October	1st to 10th	Day	13% 7% 34% 28% 13% 4	300
	11th to 20th	Day	21% 20% 32% 18% 8% 1	300
	21st to end	Day	33% 19% 31% 16% 2	330
November	1st to 10th	Day	18% 15% 37% 20% 7% 2	300
	11th to 20th	Day	26% 18% 30% 19% 6% 2	300
	21st to end	Day	30% 16% 28% 22% 4 1	300
December	1st to 10th	Day	20% 24% 34% 14% 6% 2	300
	11th to 20th	Day	23% 21% 36% 15% 3 1	300
	21st to end	Day	32% 25% 32% 10% 2	330
January	1st to 10th	Night	20% 18% 36% 22% 4 1	1000
	11th to 20th	Night	24% 20% 34% 18% 4	1000
	21st to end	Night	21% 18% 37% 23% 2	1100
February	1st to 10th	Night	23% 18% 37% 19% 2	1000
	11th to 20th	Night	23% 20% 34% 21% 2	910
	21st to end	Night	26% 18% 35% 18% 3	660
March	1st to 10th	Night	24% 17% 37% 19% 3	651
	11th to 20th	Night	23% 15% 34% 25% 3	600
	21st to end	Night	28% 18% 32% 19% 3	660
April	1st to 10th	Night	18% 17% 36% 24% 4	600
	11th to 20th	Night	21% 14% 35% 24% 5%	593
	21st to end	Night	21% 12% 37% 24% 6%	600
May	1st to 10th	Night	18% 8% 33% 33% 8%	600
	11th to 20th	Night	16% 8% 30% 31% 14% 1	591
	21st to end	Night	13% 7% 29% 32% 18% 1	650
June	1st to 10th	Night	11% 4 19% 40% 24% 2	600
	11th to 20th	Night	8% 3 25% 43% 20% 1	600
	21st to end	Night	4 3 28% 45% 19% 2	600
July	1st to 10th	Night	11% 1 14% 36% 32% 6%	570
	11th to 20th	Night	4 2 18% 44% 31% 2	552
	21st to end	Night	6% 2 18% 40% 32% 2	624
August	1st to 10th	Night	8% 2 14% 43% 32% 1	567
	11th to 20th	Night	9% 3 14% 42% 30% 3	564
	21st to end	Night	7% 3 15% 37% 35% 3	627
September	1st to 10th	Night	12% 2 17% 38% 26% 5%	570
	11th to 20th	Night	11% 3 17% 37% 28% 4	570
	21st to end	Night	10% 6% 23% 36% 21% 4	683
October	1st to 10th	Night	10% 7% 27% 31% 22% 3	760
	11th to 20th	Night	16% 13% 34% 27% 9% 1	760
	21st to end	Night	23% 13% 33% 24% 7%	836
November	1st to 10th	Night	15% 12% 36% 28% 9%	780
	11th to 20th	Night	18% 17% 32% 26% 7%	800
	21st to end	Night	23% 14% 32% 24% 6%	999
December	1st to 10th	Night	22% 15% 35% 24% 5% 1	1000
	11th to 20th	Night	25% 14% 32% 25% 4	1000
	21st to end	Night	28% 18% 32% 21% 2	1100

Page generated at 2025-07-03 00:30:17. Version ac07

Copyright © 2025 Attilla Danko.