Tamora
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tamora clear sky chart from 2005-11-06 to 2024-11-11.

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	10% 7% 3 7% 4 4 4 3 5% 7% 46%	101183
	Night	10% 6% 2 6% 4 3 4 3 5% 7% 50%	98052
Transparency	Day	36% 6% 13% 25% 17% 3	104875
	Night	33% 6% 13% 27% 19% 3	102489
Seeing	Day	13% 9% 31% 29% 14% 3	15800
	Night	12% 9% 34% 34% 10% 1	25670

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	9% 11% 4 11% 7% 7% 5% 3 6% 7% 30%	2847
	11th to 20th	Day	7% 12% 5% 8% 4 4 6% 4 5% 6% 38%	2850
	21st to end	Day	7% 11% 5% 13% 5% 5% 4 3 4 5% 37%	3135
February	1st to 10th	Day	9% 11% 3 9% 5% 4 4 4 6% 7% 37%	1710
	11th to 20th	Day	8% 9% 2 8% 5% 5% 4 4 4 8% 43%	1767
	21st to end	Day	9% 8% 3 7% 4 4 4 3 6% 7% 46%	1570
March	1st to 10th	Day	11% 8% 3 7% 4 3 3 2 3 5% 52%	3311
	11th to 20th	Day	11% 7% 2 5% 4 3 3 3 4 5% 51%	3480
	21st to end	Day	18% 12% 3 9% 4 3 4 4 6% 7% 31%	3814
April	1st to 10th	Day	13% 7% 2 6% 3 3 4 3 5% 8% 45%	2091
	11th to 20th	Day	14% 8% 3 6% 4 4 4 4 5% 7% 41%	2433
	21st to end	Day	19% 8% 2 6% 4 4 4 3 5% 7% 38%	2470
May	1st to 10th	Day	15% 8% 2 6% 4 4 4 4 6% 9% 39%	4082
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 4 6% 46%	4082
	21st to end	Day	14% 7% 2 6% 5% 4 5% 4 6% 8% 41%	4477
June	1st to 10th	Day	6% 4 2 4 4 4 4 5% 7% 8% 52%	2470
	11th to 20th	Day	9% 5% 2 5% 4 5% 4 4 6% 8% 48%	2477
	21st to end	Day	5% 5% 2 4 4 5% 5% 4 7% 8% 50%	2660
July	1st to 10th	Day	12% 5% 2 5% 3 4 4 4 6% 9% 46%	4280
	11th to 20th	Day	7% 4 2 6% 5% 4 4 4 6% 8% 51%	4120
	21st to end	Day	4 4 1 5% 4 4 4 4 8% 10% 52%	4465
August	1st to 10th	Day	7% 4 2 6% 5% 5% 6% 4 7% 9% 45%	4104
	11th to 20th	Day	13% 6% 2 7% 4 4 4 4 6% 8% 43%	4041
	21st to end	Day	6% 4 2 5% 4 4 5% 4 5% 8% 54%	4532
September	1st to 10th	Day	11% 5% 1 5% 3 4 4 3 5% 6% 54%	2123
	11th to 20th	Day	9% 5% 2 5% 4 3 4 3 4 7% 55%	2090
	21st to end	Day	9% 4 1 4 2 3 3 3 5% 6% 60%	2090
October	1st to 10th	Day	12% 6% 3 5% 4 4 3 2 3 5% 54%	1995
	11th to 20th	Day	10% 5% 2 5% 2 3 3 3 3 5% 58%	1900
	21st to end	Day	13% 7% 2 5% 4 4 2 3 3 5% 52%	2052
November	1st to 10th	Day	9% 7% 2 5% 3 3 3 3 6% 7% 53%	1763
	11th to 20th	Day	8% 6% 3 6% 4 4 4 3 5% 7% 51%	1710
	21st to end	Day	12% 8% 2 6% 4 3 3 3 4 7% 46%	1614
December	1st to 10th	Day	8% 7% 2 7% 4 4 4 4 7% 7% 48%	1520
	11th to 20th	Day	7% 8% 4 8% 6% 4 4 3 6% 7% 43%	1923
	21st to end	Day	14% 10% 5% 14% 5% 5% 4 4 5% 6% 29%	3135
January	1st to 10th	Night	7% 11% 4 14% 6% 3 5% 4 5% 7% 33%	4108
	11th to 20th	Night	7% 9% 2 7% 4 4 7% 4 5% 6% 43%	4120
	21st to end	Night	10% 11% 5% 12% 4 3 3 3 4 6% 39%	4532
February	1st to 10th	Night	10% 11% 3 7% 5% 4 5% 4 5% 5% 41%	2470
	11th to 20th	Night	8% 8% 2 7% 5% 5% 5% 4 6% 8% 44%	2315
	21st to end	Night	9% 8% 2 6% 4 4 3 3 5% 6% 52%	1884
March	1st to 10th	Night	11% 6% 2 5% 3 3 4 2 4 5% 56%	3546
	11th to 20th	Night	11% 6% 2 4 3 3 3 2 4 6% 58%	3480
	21st to end	Night	17% 8% 2 7% 4 4 4 4 6% 8% 36%	3817
April	1st to 10th	Night	11% 7% 2 6% 3 3 4 4 5% 7% 48%	2088
	11th to 20th	Night	11% 8% 2 5% 4 4 4 3 6% 7% 46%	1694
	21st to end	Night	15% 7% 2 5% 4 3 4 4 4 7% 45%	1710
May	1st to 10th	Night	19% 7% 2 4 3 3 3 3 4 6% 45%	2823
	11th to 20th	Night	10% 6% 2 5% 4 4 4 3 5% 7% 50%	2823
	21st to end	Night	14% 6% 2 5% 4 4 4 3 5% 8% 44%	3090
June	1st to 10th	Night	5% 4 2 4 3 4 4 4 6% 10% 55%	1710
	11th to 20th	Night	7% 4 1 5% 4 4 4 4 6% 9% 52%	1673
	21st to end	Night	4 3 1 4 4 4 4 3 6% 8% 59%	1520
July	1st to 10th	Night	9% 5% 2 5% 3 3 4 3 5% 7% 54%	2681
	11th to 20th	Night	5% 3 1 4 2 3 4 4 6% 9% 59%	2850
	21st to end	Night	3 2 1 3 3 3 4 4 5% 10% 62%	3098
August	1st to 10th	Night	4 4 1 5% 4 3 3 4 6% 11% 55%	2836
	11th to 20th	Night	12% 5% 2 4 4 4 4 3 5% 8% 51%	2798
	21st to end	Night	5% 3 2 5% 4 3 3 3 5% 9% 57%	3135
September	1st to 10th	Night	8% 4 1 4 3 2 3 3 4 6% 62%	2052
	11th to 20th	Night	8% 3 1 4 3 3 3 3 6% 8% 59%	2090
	21st to end	Night	8% 4 2 4 3 3 3 3 5% 6% 60%	2090
October	1st to 10th	Night	13% 4 2 5% 3 3 4 4 6% 5% 52%	2165
	11th to 20th	Night	11% 5% 2 4 3 2 3 2 3 5% 60%	2280
	21st to end	Night	13% 5% 2 4 2 2 4 3 4 5% 55%	2543
November	1st to 10th	Night	7% 4 2 5% 3 3 3 3 5% 6% 58%	2535
	11th to 20th	Night	9% 6% 2 4 4 3 3 3 5% 6% 55%	2477
	21st to end	Night	11% 6% 2 4 3 3 3 3 5% 6% 54%	2562
December	1st to 10th	Night	7% 7% 3 6% 4 4 4 3 6% 7% 50%	2660
	11th to 20th	Night	8% 7% 2 6% 3 3 3 3 5% 7% 52%	3265
	21st to end	Night	16% 11% 4 11% 4 3 4 3 4 5% 35%	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	53% 6% 13% 19% 8% 1	2848
	11th to 20th	Day	46% 5% 17% 19% 11% 1	2850
	21st to end	Day	49% 5% 12% 19% 13% 1	3135
February	1st to 10th	Day	45% 6% 16% 22% 10% 2	1710
	11th to 20th	Day	39% 6% 13% 24% 15% 3	1776
	21st to end	Day	38% 5% 12% 25% 16% 4	1570
March	1st to 10th	Day	36% 4 9% 26% 22% 3	3311
	11th to 20th	Day	35% 5% 11% 28% 20% 1	3480
	21st to end	Day	49% 9% 22% 15% 5% 1	3814
April	1st to 10th	Day	38% 6% 13% 25% 16% 2	2091
	11th to 20th	Day	41% 6% 13% 23% 13% 3	2433
	21st to end	Day	44% 7% 11% 25% 12% 1	2470
May	1st to 10th	Day	40% 7% 13% 23% 14% 3	4120
	11th to 20th	Day	38% 7% 11% 25% 18% 1	4086
	21st to end	Day	40% 8% 14% 26% 12% 1	4489
June	1st to 10th	Day	27% 8% 17% 32% 13% 2	2470
	11th to 20th	Day	32% 8% 12% 30% 16% 2	2477
	21st to end	Day	28% 9% 15% 29% 15% 4	2660
July	1st to 10th	Day	35% 6% 13% 28% 16% 1	4215
	11th to 20th	Day	29% 7% 12% 30% 18% 3	4051
	21st to end	Day	23% 8% 17% 27% 21% 4	4325
August	1st to 10th	Day	33% 8% 16% 25% 15% 4	4090
	11th to 20th	Day	38% 7% 15% 22% 17% 1	4080
	21st to end	Day	28% 7% 15% 25% 19% 7%	4531
September	1st to 10th	Day	31% 6% 10% 29% 18% 6%	2123
	11th to 20th	Day	29% 5% 12% 30% 22% 2	2090
	21st to end	Day	25% 4 10% 32% 27% 1	2090
October	1st to 10th	Day	21% 3 7% 19% 45% 5%	3320
	11th to 20th	Day	20% 4 11% 31% 25% 8%	3140
	21st to end	Day	32% 4 12% 28% 22% 3	3368
November	1st to 10th	Day	31% 4 13% 29% 21% 3	1763
	11th to 20th	Day	33% 4 13% 27% 21% 2	1710
	21st to end	Day	39% 4 10% 29% 15% 3	1614
December	1st to 10th	Day	34% 6% 17% 28% 13% 2	1520
	11th to 20th	Day	40% 6% 14% 30% 10%	1920
	21st to end	Day	55% 6% 10% 19% 10% 1	3135
January	1st to 10th	Night	48% 7% 12% 20% 12% 1	4108
	11th to 20th	Night	40% 5% 15% 26% 13% 1	4120
	21st to end	Night	47% 5% 13% 20% 15% 1	4532
February	1st to 10th	Night	45% 5% 13% 21% 13% 3	2470
	11th to 20th	Night	37% 6% 14% 24% 15% 3	2316
	21st to end	Night	34% 4 11% 23% 22% 6%	1884
March	1st to 10th	Night	30% 5% 8% 28% 25% 3	3546
	11th to 20th	Night	30% 4 9% 28% 25% 5%	3480
	21st to end	Night	44% 8% 22% 20% 6% 1	3817
April	1st to 10th	Night	35% 6% 12% 26% 19% 3	2088
	11th to 20th	Night	36% 6% 12% 26% 17% 3	1694
	21st to end	Night	38% 7% 11% 25% 17% 1	1710
May	1st to 10th	Night	40% 6% 10% 25% 17% 2	2850
	11th to 20th	Night	33% 6% 11% 28% 21% 1	2824
	21st to end	Night	38% 7% 14% 22% 18% 2	3099
June	1st to 10th	Night	25% 7% 18% 30% 17% 2	1710
	11th to 20th	Night	26% 8% 15% 29% 18% 4	1673
	21st to end	Night	21% 8% 15% 33% 20% 4	1520
July	1st to 10th	Night	30% 6% 12% 32% 18% 3	2637
	11th to 20th	Night	21% 6% 14% 33% 22% 3	2796
	21st to end	Night	16% 7% 17% 31% 26% 3	2999
August	1st to 10th	Night	22% 7% 19% 28% 19% 5%	2826
	11th to 20th	Night	33% 5% 15% 29% 16% 1	2825
	21st to end	Night	24% 6% 17% 29% 16% 8%	3135
September	1st to 10th	Night	24% 4 11% 30% 23% 8%	2052
	11th to 20th	Night	24% 6% 12% 31% 23% 4	2090
	21st to end	Night	26% 4 8% 29% 28% 4	2090
October	1st to 10th	Night	20% 4 7% 17% 45% 7%	3607
	11th to 20th	Night	21% 3 8% 31% 27% 9%	3779
	21st to end	Night	29% 4 9% 31% 24% 3	4179
November	1st to 10th	Night	26% 5% 13% 27% 25% 5%	2535
	11th to 20th	Night	30% 4 12% 30% 21% 4	2477
	21st to end	Night	31% 4 13% 27% 21% 3	2562
December	1st to 10th	Night	33% 5% 15% 31% 15% 2	2660
	11th to 20th	Night	32% 4 13% 37% 13% 1	3267
	21st to end	Night	51% 6% 10% 23% 9% 1	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	16% 15% 36% 23% 7% 2	270
	11th to 20th	Day	19% 16% 34% 24% 6% 1	270
	21st to end	Day	14% 9% 45% 24% 7% 1	297
February	1st to 10th	Day	15% 17% 46% 19% 4	270
	11th to 20th	Day	12% 13% 39% 26% 9%	270
	21st to end	Day	12% 19% 48% 18% 4	225
March	1st to 10th	Day	14% 14% 43% 21% 6% 1	270
	11th to 20th	Day	24% 11% 37% 21% 5% 1	270
	21st to end	Day	28% 18% 37% 13% 4	297
April	1st to 10th	Day	18% 17% 45% 17% 3	271
	11th to 20th	Day	19% 17% 38% 21% 6%	631
	21st to end	Day	23% 16% 30% 20% 9% 2	650
May	1st to 10th	Day	18% 11% 36% 25% 9% 1	653
	11th to 20th	Day	18% 11% 32% 26% 11% 3	675
	21st to end	Day	19% 8% 29% 31% 11% 2	734
June	1st to 10th	Day	6% 6% 25% 36% 22% 5%	680
	11th to 20th	Day	10% 5% 34% 33% 15% 3	680
	21st to end	Day	6% 7% 33% 36% 16% 2	680
July	1st to 10th	Day	10% 4 19% 34% 27% 7%	671
	11th to 20th	Day	6% 4 21% 39% 23% 7%	668
	21st to end	Day	6% 2 19% 39% 28% 5%	739
August	1st to 10th	Day	8% 4 20% 40% 23% 5%	676
	11th to 20th	Day	9% 3 21% 42% 22% 3	665
	21st to end	Day	11% 3 21% 38% 23% 5%	748
September	1st to 10th	Day	12% 4 26% 36% 17% 5%	333
	11th to 20th	Day	5% 4 31% 39% 17% 5%	300
	21st to end	Day	12% 10% 32% 29% 14% 3	300
October	1st to 10th	Day	19% 6% 24% 34% 12% 5%	300
	11th to 20th	Day	11% 14% 42% 23% 10% 1	300
	21st to end	Day	18% 14% 39% 19% 9% 1	330
November	1st to 10th	Day	17% 18% 32% 25% 7% 2	300
	11th to 20th	Day	13% 13% 47% 19% 8%	270
	21st to end	Day	23% 13% 30% 23% 9% 1	270
December	1st to 10th	Day	9% 13% 42% 28% 7% 1	270
	11th to 20th	Day	16% 11% 39% 27% 7%	270
	21st to end	Day	18% 15% 45% 20% 1	297
January	1st to 10th	Night	12% 13% 35% 32% 7% 1	950
	11th to 20th	Night	13% 12% 38% 29% 7% 1	950
	21st to end	Night	15% 9% 41% 30% 5%	1045
February	1st to 10th	Night	16% 11% 41% 29% 4	950
	11th to 20th	Night	11% 11% 43% 31% 4 1	841
	21st to end	Night	13% 13% 43% 25% 5%	628
March	1st to 10th	Night	13% 14% 38% 29% 6%	650
	11th to 20th	Night	17% 11% 38% 27% 7%	570
	21st to end	Night	21% 11% 40% 23% 6%	627
April	1st to 10th	Night	16% 13% 43% 24% 4	570
	11th to 20th	Night	15% 15% 40% 26% 3 1	563
	21st to end	Night	19% 9% 38% 26% 7% 1	570
May	1st to 10th	Night	19% 7% 35% 29% 9%	570
	11th to 20th	Night	15% 8% 34% 33% 10% 1	561
	21st to end	Night	14% 9% 30% 34% 12% 1	617
June	1st to 10th	Night	8% 4 24% 47% 16% 1	570
	11th to 20th	Night	9% 4 31% 44% 12%	570
	21st to end	Night	4 5% 31% 44% 16%	570
July	1st to 10th	Night	9% 2 17% 44% 28%	555
	11th to 20th	Night	3 1 19% 53% 21% 2	552
	21st to end	Night	3 2 16% 55% 24% 1	624
August	1st to 10th	Night	5% 2 20% 50% 22% 2	567
	11th to 20th	Night	8% 1 22% 49% 19% 1	564
	21st to end	Night	8% 2 24% 41% 23% 2	627
September	1st to 10th	Night	8% 3 27% 42% 19% 1	570
	11th to 20th	Night	11% 2 30% 41% 16% 1	570
	21st to end	Night	10% 6% 34% 35% 15% 1	570
October	1st to 10th	Night	17% 7% 30% 33% 13% 1	645
	11th to 20th	Night	13% 10% 39% 31% 7%	760
	21st to end	Night	17% 11% 31% 31% 9%	871
November	1st to 10th	Night	10% 11% 36% 34% 9% 1	975
	11th to 20th	Night	12% 11% 40% 31% 6%	953
	21st to end	Night	14% 11% 37% 29% 9% 1	950
December	1st to 10th	Night	12% 12% 41% 30% 6%	950
	11th to 20th	Night	14% 11% 36% 32% 6%	950
	21st to end	Night	17% 12% 38% 28% 5%	1045

Page generated at 2024-11-08 05:44:52. Version ac07

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