Boktuklo Trail Head
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Boktuklo Trail Head clear sky chart from 2005-11-06 to 2024-08-15.

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	15% 7% 2 6% 4 4 4 3 5% 6% 43%	95429
	Night	14% 7% 2 5% 4 3 3 3 5% 6% 49%	93352
Transparency	Day	41% 5% 10% 21% 18% 4	95204
	Night	36% 5% 10% 22% 21% 7%	93183
Seeing	Day	18% 12% 26% 25% 16% 4	15050
	Night	17% 11% 24% 29% 17% 2	24849

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	15% 10% 5% 6% 3 3 3 2 3 5% 46%	2847
	11th to 20th	Day	9% 7% 3 5% 4 3 3 3 3 5% 55%	2850
	21st to end	Day	21% 8% 2 5% 3 2 3 2 3 4 45%	3135
February	1st to 10th	Day	22% 10% 3 6% 4 4 3 2 2 4 40%	1710
	11th to 20th	Day	19% 10% 2 6% 4 4 4 3 4 5% 40%	1762
	21st to end	Day	23% 9% 3 6% 3 3 3 2 4 5% 40%	1698
March	1st to 10th	Day	20% 9% 3 6% 4 3 3 3 3 4 42%	3436
	11th to 20th	Day	16% 8% 3 7% 5% 4 4 3 5% 6% 39%	3480
	21st to end	Day	20% 11% 3 6% 4 3 3 3 4 5% 37%	3814
April	1st to 10th	Day	17% 8% 3 5% 5% 4 4 3 4 6% 42%	2138
	11th to 20th	Day	19% 6% 2 7% 4 5% 4 3 4 5% 41%	2254
	21st to end	Day	20% 8% 2 6% 5% 5% 4 3 4 5% 39%	2280
May	1st to 10th	Day	25% 8% 2 5% 4 4 3 3 4 5% 36%	4080
	11th to 20th	Day	14% 6% 2 8% 4 4 4 4 6% 6% 41%	4082
	21st to end	Day	21% 8% 3 8% 5% 4 4 3 5% 6% 32%	4477
June	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 4 6% 9% 42%	2470
	11th to 20th	Day	9% 6% 2 6% 6% 6% 5% 5% 6% 6% 43%	2470
	21st to end	Day	5% 6% 2 4 4 5% 4 5% 6% 9% 50%	2470
July	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 7% 9% 43%	4120
	11th to 20th	Day	5% 3 1 5% 4 4 5% 4 6% 8% 55%	4120
	21st to end	Day	11% 6% 2 8% 6% 6% 6% 5% 7% 9% 33%	4465
August	1st to 10th	Day	5% 4 2 6% 5% 6% 7% 5% 7% 9% 45%	2458
	11th to 20th	Day	10% 5% 3 6% 5% 4 5% 4 7% 9% 43%	2334
	21st to end	Day	6% 5% 2 7% 5% 6% 7% 5% 8% 9% 41%	2376
September	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 5% 6% 48%	2102
	11th to 20th	Day	11% 4 2 6% 5% 5% 4 5% 6% 7% 46%	1980
	21st to end	Day	10% 4 2 5% 4 3 4 4 5% 6% 53%	1980
October	1st to 10th	Day	10% 5% 2 7% 4 2 4 3 5% 6% 53%	1816
	11th to 20th	Day	16% 4 2 4 3 3 2 2 3 3 57%	1800
	21st to end	Day	20% 7% 2 4 2 3 3 2 4 4 48%	1980
November	1st to 10th	Day	14% 6% 2 5% 4 3 2 2 5% 6% 50%	1858
	11th to 20th	Day	12% 6% 2 4 3 3 3 2 4 5% 55%	1871
	21st to end	Day	20% 6% 2 4 3 4 3 2 3 5% 49%	1710
December	1st to 10th	Day	19% 7% 2 4 3 3 3 2 4 5% 48%	1710
	11th to 20th	Day	16% 10% 2 6% 4 4 3 3 4 5% 42%	2161
	21st to end	Day	19% 12% 3 6% 4 4 3 3 4 6% 36%	3135
January	1st to 10th	Night	12% 9% 4 6% 4 3 3 3 4 5% 46%	4108
	11th to 20th	Night	12% 7% 2 5% 3 2 3 2 4 4 55%	4120
	21st to end	Night	23% 7% 3 4 3 2 2 3 4 4 46%	4532
February	1st to 10th	Night	19% 9% 3 5% 4 2 4 3 4 4 42%	2470
	11th to 20th	Night	18% 9% 3 6% 4 3 3 3 4 5% 44%	2322
	21st to end	Night	18% 8% 2 6% 2 3 3 3 4 5% 46%	1756
March	1st to 10th	Night	22% 10% 3 6% 3 2 3 2 4 4 40%	3419
	11th to 20th	Night	17% 8% 2 5% 4 3 3 2 4 5% 47%	3480
	21st to end	Night	15% 8% 2 8% 5% 4 3 3 5% 6% 41%	3817
April	1st to 10th	Night	14% 7% 3 5% 4 4 3 3 5% 5% 47%	2040
	11th to 20th	Night	15% 7% 2 6% 4 4 3 2 4 6% 47%	1875
	21st to end	Night	14% 7% 2 6% 4 3 3 3 5% 7% 45%	1897
May	1st to 10th	Night	21% 9% 2 5% 4 3 3 4 5% 7% 37%	2823
	11th to 20th	Night	15% 6% 2 6% 4 4 4 4 6% 7% 44%	2823
	21st to end	Night	17% 7% 2 6% 4 4 3 3 6% 8% 40%	3090
June	1st to 10th	Night	6% 5% 2 5% 3 3 3 4 5% 8% 56%	1710
	11th to 20th	Night	6% 5% 1 4 4 2 3 3 5% 9% 57%	1710
	21st to end	Night	5% 4 1 3 2 3 3 3 6% 9% 63%	1710
July	1st to 10th	Night	8% 4 2 5% 4 4 4 4 6% 9% 50%	2850
	11th to 20th	Night	5% 2 1 3 2 2 3 3 5% 8% 65%	2850
	21st to end	Night	9% 7% 2 6% 3 4 5% 4 6% 8% 45%	3098
August	1st to 10th	Night	3 2 1 4 3 4 4 4 7% 9% 59%	1701
	11th to 20th	Night	7% 3 2 4 4 3 4 4 7% 9% 51%	1663
	21st to end	Night	5% 4 2 6% 4 4 4 3 5% 11% 53%	1980
September	1st to 10th	Night	5% 6% 2 4 4 3 3 4 6% 7% 57%	1854
	11th to 20th	Night	9% 4 2 5% 4 4 4 4 6% 7% 50%	1980
	21st to end	Night	9% 4 1 4 3 3 3 3 4 5% 61%	1980
October	1st to 10th	Night	9% 4 2 4 3 3 3 3 5% 7% 57%	2124
	11th to 20th	Night	15% 4 2 4 2 2 3 2 4 5% 58%	2160
	21st to end	Night	18% 7% 2 4 3 3 2 2 3 3 54%	2376
November	1st to 10th	Night	11% 6% 2 4 3 3 3 3 3 5% 57%	2220
	11th to 20th	Night	10% 7% 2 4 3 3 3 3 4 4 57%	2306
	21st to end	Night	17% 9% 3 5% 3 2 2 2 4 5% 48%	2470
December	1st to 10th	Night	17% 7% 2 5% 3 3 3 3 4 5% 48%	2470
	11th to 20th	Night	16% 7% 3 6% 5% 4 3 2 4 3 46%	3036
	21st to end	Night	18% 9% 3 6% 4 3 4 2 4 5% 42%	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	43% 3 5% 23% 21% 4	2848
	11th to 20th	Day	33% 3 13% 26% 22% 4	2850
	21st to end	Day	44% 4 5% 18% 22% 7%	3135
February	1st to 10th	Day	51% 2 8% 15% 20% 4	1710
	11th to 20th	Day	47% 4 6% 19% 19% 5%	1771
	21st to end	Day	48% 3 5% 15% 20% 8%	1698
March	1st to 10th	Day	46% 3 7% 13% 20% 10%	3436
	11th to 20th	Day	45% 6% 11% 17% 16% 5%	3480
	21st to end	Day	49% 5% 8% 21% 16% 2	3814
April	1st to 10th	Day	44% 4 9% 18% 19% 6%	2138
	11th to 20th	Day	45% 5% 7% 20% 18% 5%	2254
	21st to end	Day	48% 6% 7% 19% 18% 3	2280
May	1st to 10th	Day	50% 5% 9% 21% 13% 2	4118
	11th to 20th	Day	40% 7% 12% 22% 18% 1	4086
	21st to end	Day	52% 7% 11% 16% 12% 3	4489
June	1st to 10th	Day	37% 8% 14% 26% 13% 2	2470
	11th to 20th	Day	38% 8% 12% 23% 18% 2	2470
	21st to end	Day	29% 7% 14% 28% 19% 2	2470
July	1st to 10th	Day	35% 7% 20% 25% 11% 1	4056
	11th to 20th	Day	25% 6% 10% 36% 21% 1	4051
	21st to end	Day	42% 9% 14% 25% 9%	4325
August	1st to 10th	Day	31% 9% 15% 29% 15% 2	2444
	11th to 20th	Day	36% 8% 14% 25% 16% 2	2334
	21st to end	Day	36% 8% 14% 26% 13% 3	2376
September	1st to 10th	Day	35% 6% 10% 22% 19% 9%	2102
	11th to 20th	Day	35% 7% 11% 22% 18% 7%	1980
	21st to end	Day	31% 7% 9% 18% 27% 9%	1980
October	1st to 10th	Day	33% 4 11% 18% 23% 11%	1816
	11th to 20th	Day	34% 2 5% 15% 30% 13%	1800
	21st to end	Day	41% 3 6% 18% 22% 10%	1980
November	1st to 10th	Day	36% 3 7% 22% 24% 7%	1858
	11th to 20th	Day	32% 4 7% 21% 26% 10%	1871
	21st to end	Day	40% 3 5% 18% 26% 7%	1710
December	1st to 10th	Day	39% 5% 8% 23% 19% 6%	1710
	11th to 20th	Day	45% 3 7% 17% 23% 6%	2159
	21st to end	Day	49% 3 8% 16% 18% 5%	3135
January	1st to 10th	Night	40% 4 7% 17% 28% 5%	4108
	11th to 20th	Night	33% 4 10% 20% 25% 6%	4120
	21st to end	Night	43% 4 7% 16% 23% 7%	4532
February	1st to 10th	Night	45% 4 9% 19% 17% 7%	2470
	11th to 20th	Night	44% 3 5% 20% 21% 6%	2323
	21st to end	Night	40% 4 8% 17% 21% 10%	1756
March	1st to 10th	Night	48% 4 5% 15% 16% 11%	3419
	11th to 20th	Night	40% 5% 8% 24% 14% 10%	3480
	21st to end	Night	42% 5% 9% 19% 21% 2	3817
April	1st to 10th	Night	39% 4 9% 19% 19% 10%	2040
	11th to 20th	Night	38% 4 8% 21% 20% 9%	1875
	21st to end	Night	38% 6% 9% 23% 22% 2	1897
May	1st to 10th	Night	47% 7% 10% 18% 13% 5%	2850
	11th to 20th	Night	37% 7% 14% 24% 16% 2	2824
	21st to end	Night	41% 8% 15% 21% 11% 5%	3099
June	1st to 10th	Night	26% 7% 16% 29% 19% 3	1710
	11th to 20th	Night	25% 6% 11% 33% 22% 3	1710
	21st to end	Night	20% 5% 13% 30% 28% 4	1710
July	1st to 10th	Night	29% 7% 21% 26% 15% 2	2805
	11th to 20th	Night	17% 5% 11% 43% 22% 2	2796
	21st to end	Night	35% 7% 15% 28% 15% 1	2999
August	1st to 10th	Night	19% 8% 16% 33% 21% 3	1691
	11th to 20th	Night	26% 7% 16% 30% 20% 2	1663
	21st to end	Night	27% 6% 14% 29% 20% 3	1980
September	1st to 10th	Night	26% 6% 12% 25% 23% 9%	1854
	11th to 20th	Night	32% 6% 12% 21% 21% 9%	1980
	21st to end	Night	26% 4 7% 23% 30% 10%	1980
October	1st to 10th	Night	26% 5% 12% 22% 21% 14%	2124
	11th to 20th	Night	30% 4 6% 15% 28% 17%	2160
	21st to end	Night	36% 3 5% 19% 25% 12%	2376
November	1st to 10th	Night	31% 3 8% 22% 25% 11%	2220
	11th to 20th	Night	31% 3 8% 20% 26% 12%	2306
	21st to end	Night	40% 3 6% 17% 27% 7%	2470
December	1st to 10th	Night	38% 4 9% 19% 22% 9%	2470
	11th to 20th	Night	43% 4 5% 15% 24% 10%	3037
	21st to end	Night	44% 3 9% 18% 20% 6%	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	27% 21% 35% 12% 5%	270
	11th to 20th	Day	27% 26% 33% 10% 3	270
	21st to end	Day	26% 27% 31% 13% 3	297
February	1st to 10th	Day	34% 20% 30% 11% 5%	270
	11th to 20th	Day	37% 26% 28% 8% 1	270
	21st to end	Day	41% 28% 22% 8% 2	225
March	1st to 10th	Day	33% 22% 30% 14% 1	270
	11th to 20th	Day	40% 23% 24% 10% 3	270
	21st to end	Day	32% 23% 35% 8% 2	297
April	1st to 10th	Day	30% 20% 33% 12% 5%	318
	11th to 20th	Day	34% 16% 31% 13% 7%	452
	21st to end	Day	26% 20% 29% 18% 6% 1	460
May	1st to 10th	Day	23% 17% 37% 19% 4 1	651
	11th to 20th	Day	19% 12% 34% 24% 8% 2	675
	21st to end	Day	16% 10% 36% 20% 16% 2	734
June	1st to 10th	Day	12% 8% 23% 32% 21% 5%	680
	11th to 20th	Day	10% 5% 29% 35% 18% 4	680
	21st to end	Day	5% 5% 25% 35% 20% 9%	680
July	1st to 10th	Day	8% 3 17% 35% 29% 7%	671
	11th to 20th	Day	4 1 16% 36% 33% 9%	668
	21st to end	Day	6% 3 13% 35% 33% 10%	739
August	1st to 10th	Day	6% 3 14% 41% 31% 6%	676
	11th to 20th	Day	11% 3 14% 37% 29% 6%	616
	21st to end	Day	8% 2 9% 32% 38% 11%	495
September	1st to 10th	Day	8% 1 9% 37% 35% 10%	392
	11th to 20th	Day	4 3 23% 39% 27% 5%	270
	21st to end	Day	16% 6% 20% 31% 21% 5%	270
October	1st to 10th	Day	8% 7% 37% 28% 17% 2	270
	11th to 20th	Day	19% 15% 37% 24% 4 1	270
	21st to end	Day	33% 15% 28% 18% 5% 1	297
November	1st to 10th	Day	16% 21% 33% 21% 7% 1	270
	11th to 20th	Day	20% 19% 39% 16% 5% 1	270
	21st to end	Day	31% 19% 29% 15% 6%	270
December	1st to 10th	Day	27% 22% 29% 17% 4 1	270
	11th to 20th	Day	30% 24% 31% 10% 5%	270
	21st to end	Day	27% 24% 36% 8% 3 1	297
January	1st to 10th	Night	21% 15% 31% 27% 6%	950
	11th to 20th	Night	24% 19% 28% 23% 5% 1	950
	21st to end	Night	21% 16% 30% 28% 5%	1045
February	1st to 10th	Night	26% 17% 28% 24% 5%	950
	11th to 20th	Night	26% 21% 29% 22% 2	848
	21st to end	Night	29% 18% 31% 19% 4	500
March	1st to 10th	Night	25% 15% 26% 29% 5%	570
	11th to 20th	Night	24% 15% 28% 29% 5% 1	570
	21st to end	Night	21% 19% 33% 21% 6%	627
April	1st to 10th	Night	19% 19% 31% 25% 6%	570
	11th to 20th	Night	21% 17% 27% 27% 8%	563
	21st to end	Night	19% 16% 32% 22% 10% 1	570
May	1st to 10th	Night	16% 10% 32% 33% 9%	570
	11th to 20th	Night	15% 8% 30% 29% 17% 1	561
	21st to end	Night	15% 6% 28% 28% 21% 2	617
June	1st to 10th	Night	8% 5% 16% 35% 34% 3	570
	11th to 20th	Night	8% 3 21% 38% 28% 1	570
	21st to end	Night	5% 2 18% 35% 35% 6%	570
July	1st to 10th	Night	4 2 10% 32% 46% 6%	555
	11th to 20th	Night	4 1 10% 33% 45% 7%	552
	21st to end	Night	5% 2 8% 33% 46% 7%	624
August	1st to 10th	Night	3 1 10% 37% 45% 5%	567
	11th to 20th	Night	8% 2 7% 37% 38% 7%	549
	21st to end	Night	6% 1 10% 36% 40% 7%	594
September	1st to 10th	Night	7% 3 10% 36% 39% 6%	540
	11th to 20th	Night	12% 2 10% 34% 37% 4	540
	21st to end	Night	10% 3 16% 33% 34% 4	540
October	1st to 10th	Night	10% 4 20% 35% 28% 3	684
	11th to 20th	Night	17% 9% 28% 29% 15% 1	720
	21st to end	Night	22% 12% 24% 26% 14% 2	792
November	1st to 10th	Night	15% 10% 29% 33% 12% 1	740
	11th to 20th	Night	16% 14% 27% 32% 11%	786
	21st to end	Night	24% 16% 25% 25% 10% 1	950
December	1st to 10th	Night	23% 13% 28% 30% 6%	950
	11th to 20th	Night	27% 14% 26% 28% 5%	950
	21st to end	Night	23% 17% 28% 25% 7%	1045

Page generated at 2024-08-12 08:52:52. Version ac07

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