Jefferson (TX)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jefferson (TX) clear sky chart from 2005-11-06 to 2024-11-30.

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	13% 6% 2 5% 4 4 4 4 5% 7% 45%	101357
	Night	13% 6% 2 5% 3 3 3 3 5% 7% 50%	98327
Transparency	Day	37% 6% 11% 21% 19% 6%	105005
	Night	33% 6% 10% 20% 22% 10%	102819
Seeing	Day	14% 9% 23% 28% 20% 6%	15241
	Night	14% 9% 25% 31% 18% 2	25063

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	19% 12% 2 5% 3 3 2 2 3 4 45%	2847
	11th to 20th	Day	19% 6% 2 4 3 3 3 2 4 4 51%	2850
	21st to end	Day	24% 8% 2 5% 3 3 2 2 2 4 44%	3135
February	1st to 10th	Day	23% 9% 2 5% 4 3 3 3 3 4 39%	1710
	11th to 20th	Day	20% 9% 3 6% 4 3 3 3 4 5% 40%	1802
	21st to end	Day	24% 7% 2 6% 3 4 3 3 3 3 43%	1727
March	1st to 10th	Day	19% 11% 3 7% 4 4 3 3 4 6% 37%	3436
	11th to 20th	Day	19% 7% 3 6% 4 4 4 3 6% 6% 37%	3480
	21st to end	Day	17% 9% 3 6% 4 4 4 3 5% 6% 39%	3814
April	1st to 10th	Day	14% 7% 3 7% 4 5% 3 2 5% 6% 45%	2152
	11th to 20th	Day	17% 7% 2 6% 4 4 4 3 6% 7% 42%	2254
	21st to end	Day	13% 6% 2 5% 5% 4 5% 4 5% 7% 44%	2280
May	1st to 10th	Day	21% 8% 3 6% 4 4 4 3 6% 7% 35%	3878
	11th to 20th	Day	14% 6% 2 5% 5% 5% 4 3 5% 7% 44%	4082
	21st to end	Day	15% 7% 3 6% 6% 5% 5% 4 7% 8% 34%	4477
June	1st to 10th	Day	8% 4 2 5% 5% 5% 6% 6% 8% 9% 41%	2470
	11th to 20th	Day	6% 4 1 5% 5% 5% 6% 5% 7% 9% 46%	2470
	21st to end	Day	5% 3 2 4 6% 5% 6% 5% 6% 10% 47%	2470
July	1st to 10th	Day	9% 5% 2 7% 5% 6% 6% 6% 8% 11% 36%	4120
	11th to 20th	Day	5% 4 2 4 4 5% 5% 5% 7% 10% 50%	4120
	21st to end	Day	13% 10% 3 7% 5% 5% 5% 4 6% 8% 34%	4465
August	1st to 10th	Day	2 1 1 3 3 3 4 3 6% 7% 66%	4104
	11th to 20th	Day	5% 2 1 4 4 4 5% 5% 7% 10% 54%	3864
	21st to end	Day	6% 4 2 6% 5% 6% 6% 6% 8% 10% 41%	4180
September	1st to 10th	Day	9% 5% 2 6% 4 4 4 4 6% 9% 47%	2250
	11th to 20th	Day	11% 6% 2 7% 5% 5% 4 5% 6% 7% 42%	2090
	21st to end	Day	8% 3 1 5% 4 4 4 3 5% 7% 57%	2085
October	1st to 10th	Day	7% 3 1 4 3 3 4 3 5% 7% 61%	1900
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 4 5% 55%	1900
	21st to end	Day	16% 6% 2 4 4 3 2 2 3 4 55%	2090
November	1st to 10th	Day	14% 7% 2 5% 4 3 3 3 4 6% 49%	1958
	11th to 20th	Day	11% 6% 2 6% 3 3 3 3 4 6% 53%	2000
	21st to end	Day	18% 8% 2 5% 3 3 4 2 3 5% 47%	1891
December	1st to 10th	Day	16% 8% 2 5% 4 3 3 3 4 5% 47%	1710
	11th to 20th	Day	16% 9% 3 5% 4 4 3 3 5% 6% 43%	2161
	21st to end	Day	16% 8% 2 7% 4 4 3 3 5% 5% 43%	3135
January	1st to 10th	Night	16% 9% 3 6% 2 3 2 2 3 4 49%	4108
	11th to 20th	Night	19% 6% 1 4 3 2 2 2 3 4 54%	4120
	21st to end	Night	24% 10% 2 4 3 2 2 2 3 3 44%	4532
February	1st to 10th	Night	18% 7% 3 5% 3 3 3 3 4 5% 46%	2470
	11th to 20th	Night	21% 8% 2 4 3 3 2 3 4 5% 45%	2277
	21st to end	Night	20% 7% 1 5% 3 4 2 3 4 5% 47%	1727
March	1st to 10th	Night	22% 8% 3 6% 4 4 3 3 4 5% 38%	3419
	11th to 20th	Night	18% 6% 3 7% 4 4 3 4 5% 7% 40%	3480
	21st to end	Night	13% 6% 3 6% 4 4 4 4 5% 6% 46%	3817
April	1st to 10th	Night	10% 4 2 5% 4 4 4 4 6% 8% 49%	2028
	11th to 20th	Night	12% 5% 3 6% 4 4 4 3 5% 6% 47%	1875
	21st to end	Night	12% 5% 2 5% 3 3 3 4 6% 7% 51%	1900
May	1st to 10th	Night	15% 7% 3 8% 4 4 4 4 6% 8% 38%	3017
	11th to 20th	Night	13% 6% 2 6% 4 3 4 3 4 8% 47%	2823
	21st to end	Night	13% 6% 2 5% 4 4 5% 4 5% 9% 42%	3090
June	1st to 10th	Night	5% 3 2 4 3 4 4 5% 6% 11% 54%	1710
	11th to 20th	Night	4 3 2 4 4 4 3 3 6% 9% 59%	1710
	21st to end	Night	5% 3 1 4 3 3 5% 4 6% 9% 56%	1710
July	1st to 10th	Night	8% 4 2 5% 5% 4 5% 4 7% 12% 46%	2850
	11th to 20th	Night	5% 3 1 4 3 3 4 3 6% 12% 56%	2850
	21st to end	Night	12% 7% 3 7% 5% 4 4 3 5% 9% 42%	3098
August	1st to 10th	Night	2 1 1 2 2 2 2 2 4 8% 74%	2836
	11th to 20th	Night	3 2 1 3 3 3 3 3 6% 12% 60%	2967
	21st to end	Night	4 3 1 5% 4 5% 5% 4 7% 10% 51%	3476
September	1st to 10th	Night	8% 4 2 5% 4 3 4 4 5% 6% 54%	1925
	11th to 20th	Night	10% 4 2 5% 4 3 4 4 6% 7% 52%	2090
	21st to end	Night	7% 3 1 3 3 3 3 3 5% 5% 62%	2090
October	1st to 10th	Night	5% 2 1 3 2 3 4 3 4 6% 66%	2266
	11th to 20th	Night	10% 5% 2 3 2 3 3 2 4 6% 60%	2280
	21st to end	Night	15% 4 1 5% 3 2 2 2 3 5% 57%	2508
November	1st to 10th	Night	13% 5% 1 4 3 4 3 2 4 5% 56%	2340
	11th to 20th	Night	9% 4 2 5% 4 4 4 3 4 4 57%	2400
	21st to end	Night	15% 7% 2 6% 3 3 3 2 4 5% 50%	2500
December	1st to 10th	Night	16% 8% 3 5% 4 3 3 3 5% 6% 47%	2470
	11th to 20th	Night	14% 7% 3 6% 5% 3 3 3 4 4 48%	3036
	21st to end	Night	17% 8% 2 5% 4 3 3 2 3 4 48%	4532

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	45% 3 5% 18% 25% 4	2848
	11th to 20th	Day	37% 4 8% 23% 24% 4	2850
	21st to end	Day	45% 4 4 16% 20% 10%	3135
February	1st to 10th	Day	49% 4 6% 15% 16% 9%	1710
	11th to 20th	Day	48% 4 5% 15% 19% 8%	1811
	21st to end	Day	46% 5% 6% 12% 21% 10%	1727
March	1st to 10th	Day	49% 6% 7% 13% 19% 6%	3436
	11th to 20th	Day	45% 7% 7% 21% 16% 4	3480
	21st to end	Day	45% 6% 8% 18% 21% 3	3814
April	1st to 10th	Day	40% 6% 8% 21% 18% 8%	2152
	11th to 20th	Day	42% 6% 9% 17% 18% 8%	2254
	21st to end	Day	38% 7% 10% 18% 22% 4	2280
May	1st to 10th	Day	47% 8% 11% 21% 10% 3	3913
	11th to 20th	Day	38% 8% 10% 21% 22% 1	4086
	21st to end	Day	43% 11% 15% 19% 10% 3	4489
June	1st to 10th	Day	34% 12% 15% 25% 14% 1	2470
	11th to 20th	Day	31% 9% 16% 24% 16% 3	2470
	21st to end	Day	30% 9% 16% 26% 17% 2	2470
July	1st to 10th	Day	39% 7% 22% 24% 7%	4056
	11th to 20th	Day	27% 7% 17% 33% 15%	4051
	21st to end	Day	47% 6% 14% 23% 10%	4325
August	1st to 10th	Day	16% 6% 15% 31% 28% 5%	4090
	11th to 20th	Day	24% 6% 21% 36% 12% 1	3903
	21st to end	Day	35% 7% 17% 25% 15% 1	4179
September	1st to 10th	Day	33% 7% 13% 20% 16% 10%	2250
	11th to 20th	Day	38% 8% 12% 17% 18% 7%	2090
	21st to end	Day	27% 7% 9% 22% 25% 11%	2085
October	1st to 10th	Day	14% 3 7% 13% 26% 37%	3160
	11th to 20th	Day	19% 3 4 16% 32% 25%	3140
	21st to end	Day	29% 4 4 21% 32% 10%	3428
November	1st to 10th	Day	35% 6% 8% 18% 23% 10%	1958
	11th to 20th	Day	33% 4 8% 17% 27% 12%	2000
	21st to end	Day	41% 4 7% 15% 24% 8%	1891
December	1st to 10th	Day	40% 5% 9% 18% 20% 8%	1710
	11th to 20th	Day	42% 5% 7% 14% 25% 8%	2159
	21st to end	Day	43% 5% 6% 16% 23% 6%	3135
January	1st to 10th	Night	39% 4 6% 13% 30% 7%	4108
	11th to 20th	Night	36% 5% 6% 18% 27% 9%	4120
	21st to end	Night	46% 3 7% 14% 20% 9%	4532
February	1st to 10th	Night	41% 4 8% 18% 17% 12%	2470
	11th to 20th	Night	43% 4 6% 17% 21% 9%	2278
	21st to end	Night	42% 4 7% 14% 19% 13%	1727
March	1st to 10th	Night	47% 6% 7% 13% 17% 10%	3419
	11th to 20th	Night	42% 7% 9% 16% 19% 6%	3480
	21st to end	Night	37% 7% 10% 18% 24% 4	3817
April	1st to 10th	Night	32% 7% 12% 21% 18% 11%	2028
	11th to 20th	Night	36% 7% 9% 18% 18% 12%	1875
	21st to end	Night	32% 5% 10% 22% 25% 5%	1900
May	1st to 10th	Night	42% 9% 11% 20% 13% 5%	3047
	11th to 20th	Night	36% 7% 13% 19% 22% 3	2824
	21st to end	Night	36% 9% 15% 23% 14% 3	3099
June	1st to 10th	Night	22% 10% 16% 30% 19% 2	1710
	11th to 20th	Night	21% 9% 15% 29% 22% 5%	1710
	21st to end	Night	23% 8% 15% 27% 25% 3	1710
July	1st to 10th	Night	31% 7% 23% 30% 8% 1	2805
	11th to 20th	Night	21% 5% 19% 36% 16% 2	2796
	21st to end	Night	40% 6% 15% 27% 11% 1	2999
August	1st to 10th	Night	10% 4 14% 32% 33% 6%	2826
	11th to 20th	Night	17% 5% 18% 40% 16% 3	2994
	21st to end	Night	28% 7% 16% 24% 23% 2	3476
September	1st to 10th	Night	29% 8% 14% 20% 19% 11%	1925
	11th to 20th	Night	30% 8% 13% 20% 20% 9%	2090
	21st to end	Night	23% 5% 10% 22% 27% 13%	2090
October	1st to 10th	Night	13% 3 5% 14% 20% 43%	3786
	11th to 20th	Night	17% 2 4 14% 34% 28%	3779
	21st to end	Night	26% 3 4 19% 32% 16%	4120
November	1st to 10th	Night	31% 5% 8% 17% 27% 12%	2340
	11th to 20th	Night	30% 5% 8% 16% 27% 15%	2400
	21st to end	Night	37% 4 7% 18% 24% 10%	2500
December	1st to 10th	Night	39% 6% 9% 18% 20% 9%	2470
	11th to 20th	Night	39% 6% 6% 14% 24% 11%	3037
	21st to end	Night	40% 5% 6% 17% 25% 8%	4532

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	24% 19% 35% 17% 4	270
	11th to 20th	Day	26% 19% 37% 15% 3	270
	21st to end	Day	26% 22% 34% 14% 3	297
February	1st to 10th	Day	31% 18% 34% 14% 3	270
	11th to 20th	Day	34% 21% 34% 9% 2	270
	21st to end	Day	38% 24% 32% 5% 2	225
March	1st to 10th	Day	24% 21% 37% 15% 4	270
	11th to 20th	Day	25% 24% 35% 13% 3	270
	21st to end	Day	24% 23% 34% 15% 3	297
April	1st to 10th	Day	22% 17% 40% 15% 5% 1	332
	11th to 20th	Day	27% 16% 29% 19% 9% 1	452
	21st to end	Day	16% 15% 33% 27% 7% 2	460
May	1st to 10th	Day	15% 14% 37% 27% 6%	524
	11th to 20th	Day	15% 8% 29% 32% 14% 3	675
	21st to end	Day	13% 7% 28% 33% 16% 3	734
June	1st to 10th	Day	9% 2 16% 38% 29% 6%	680
	11th to 20th	Day	7% 2 17% 42% 26% 6%	680
	21st to end	Day	4 2 17% 38% 29% 10%	680
July	1st to 10th	Day	9% 3 14% 34% 30% 11%	671
	11th to 20th	Day	4 3 7% 35% 41% 10%	668
	21st to end	Day	8% 9% 37% 36% 10%	739
August	1st to 10th	Day	4 1 7% 33% 42% 13%	676
	11th to 20th	Day	8% 1 7% 33% 41% 9%	566
	21st to end	Day	10% 1 7% 24% 42% 16%	539
September	1st to 10th	Day	9% 2 9% 29% 38% 12%	460
	11th to 20th	Day	7% 2 13% 32% 32% 14%	300
	21st to end	Day	10% 4 16% 34% 26% 10%	300
October	1st to 10th	Day	5% 3 23% 41% 23% 4	300
	11th to 20th	Day	10% 10% 32% 33% 11% 4	300
	21st to end	Day	23% 14% 26% 25% 9% 3	330
November	1st to 10th	Day	18% 10% 30% 29% 12% 1	300
	11th to 20th	Day	13% 13% 38% 29% 7%	300
	21st to end	Day	23% 17% 30% 22% 6% 1	299
December	1st to 10th	Day	19% 19% 36% 14% 9% 2	270
	11th to 20th	Day	26% 15% 36% 17% 6% 1	270
	21st to end	Day	21% 19% 41% 14% 4 2	297
January	1st to 10th	Night	21% 15% 32% 25% 6%	950
	11th to 20th	Night	24% 15% 30% 25% 6% 1	950
	21st to end	Night	22% 14% 34% 26% 4	1045
February	1st to 10th	Night	23% 14% 35% 24% 4	950
	11th to 20th	Night	28% 15% 34% 20% 3	803
	21st to end	Night	24% 20% 34% 19% 2	471
March	1st to 10th	Night	22% 14% 33% 25% 7%	570
	11th to 20th	Night	19% 14% 35% 25% 5% 1	570
	21st to end	Night	17% 12% 39% 25% 7%	627
April	1st to 10th	Night	12% 16% 39% 25% 8%	570
	11th to 20th	Night	13% 16% 36% 24% 11% 1	563
	21st to end	Night	14% 10% 39% 26% 10% 1	570
May	1st to 10th	Night	10% 9% 38% 31% 11% 1	570
	11th to 20th	Night	12% 6% 32% 32% 17% 2	561
	21st to end	Night	8% 5% 27% 36% 20% 3	617
June	1st to 10th	Night	4 2 12% 41% 38% 3	570
	11th to 20th	Night	4 2 16% 46% 30% 2	570
	21st to end	Night	4 2 14% 37% 36% 7%	570
July	1st to 10th	Night	6% 1 7% 39% 41% 7%	555
	11th to 20th	Night	4 1 6% 38% 44% 7%	552
	21st to end	Night	5% 1 9% 37% 39% 9%	624
August	1st to 10th	Night	3 1 6% 39% 44% 7%	567
	11th to 20th	Night	5% 1 6% 41% 40% 6%	564
	21st to end	Night	6% 1 7% 37% 41% 7%	627
September	1st to 10th	Night	10% 1 10% 33% 39% 8%	570
	11th to 20th	Night	10% 1 11% 32% 39% 7%	570
	21st to end	Night	8% 2 11% 40% 36% 3	570
October	1st to 10th	Night	7% 2 13% 44% 29% 5%	746
	11th to 20th	Night	13% 6% 25% 35% 19% 2	760
	21st to end	Night	17% 8% 27% 29% 17% 2	836
November	1st to 10th	Night	14% 6% 27% 37% 15% 1	780
	11th to 20th	Night	12% 11% 30% 36% 11%	800
	21st to end	Night	18% 14% 30% 26% 12% 1	900
December	1st to 10th	Night	18% 13% 32% 29% 8%	950
	11th to 20th	Night	21% 13% 28% 31% 6%	950
	21st to end	Night	23% 15% 30% 27% 6%	1045

Page generated at 2024-11-27 16:30:55. Version ac07

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