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 2024-01-22.

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	14% 6% 3 5% 5% 3 4 4 5% 7% 44%	75057
	Night	13% 6% 2 4 4 2 3 4 5% 6% 50%	74910
Transparency	Day	40% 6% 10% 21% 19% 5%	74781
	Night	34% 5% 10% 22% 22% 7%	74706
Seeing	Day	18% 12% 26% 25% 16% 4	14195
	Night	17% 11% 24% 29% 17% 2	24175

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% 9% 3 4 5% 2 4 2 4 5% 48%	1707
	11th to 20th	Day	14% 7% 3 5% 5% 3 4 4 4 5% 48%	1710
	21st to end	Day	15% 8% 3 5% 5% 1 3 3 4 4 48%	1791
February	1st to 10th	Day	22% 10% 3 5% 4 3 3 3 2 4 40%	1620
	11th to 20th	Day	20% 10% 3 5% 5% 3 4 4 4 5% 38%	1667
	21st to end	Day	25% 8% 3 5% 3 2 3 3 4 5% 39%	1601
March	1st to 10th	Day	19% 7% 2 5% 5% 3 4 4 3 5% 44%	1980
	11th to 20th	Day	22% 9% 4 6% 5% 3 3 3 4 4 39%	1980
	21st to end	Day	21% 10% 3 5% 4 2 3 4 4 6% 38%	2178
April	1st to 10th	Day	16% 7% 4 4 5% 3 4 3 4 7% 42%	2025
	11th to 20th	Day	18% 6% 3 6% 4 3 5% 4 4 5% 42%	2134
	21st to end	Day	19% 7% 3 5% 5% 4 4 4 4 5% 39%	2160
May	1st to 10th	Day	19% 8% 3 4 4 3 4 4 4 6% 41%	2338
	11th to 20th	Day	16% 7% 3 7% 5% 3 5% 5% 6% 7% 38%	2302
	21st to end	Day	14% 7% 3 8% 6% 4 5% 5% 5% 7% 35%	2531
June	1st to 10th	Day	11% 6% 2 5% 5% 3 5% 5% 6% 9% 42%	2340
	11th to 20th	Day	9% 6% 3 5% 6% 5% 6% 6% 6% 7% 42%	2340
	21st to end	Day	6% 5% 2 4 4 4 5% 5% 6% 9% 50%	2340
July	1st to 10th	Day	10% 5% 2 6% 7% 4 6% 6% 9% 11% 34%	2340
	11th to 20th	Day	5% 2 1 5% 5% 3 7% 6% 7% 11% 46%	2340
	21st to end	Day	7% 4 2 5% 5% 5% 7% 7% 7% 10% 42%	2546
August	1st to 10th	Day	5% 4 2 5% 6% 4 7% 7% 7% 10% 44%	2328
	11th to 20th	Day	10% 5% 3 5% 6% 2 6% 6% 7% 9% 42%	2280
	21st to end	Day	6% 4 2 5% 6% 4 8% 7% 8% 9% 41%	2376
September	1st to 10th	Day	12% 5% 2 5% 5% 3 5% 5% 5% 6% 48%	2102
	11th to 20th	Day	11% 4 2 6% 6% 4 4 6% 6% 7% 46%	1980
	21st to end	Day	10% 3 2 5% 4 2 4 5% 5% 6% 53%	1980
October	1st to 10th	Day	10% 5% 2 6% 4 2 3 4 5% 6% 53%	1816
	11th to 20th	Day	16% 4 2 4 3 2 3 3 3 3 57%	1800
	21st to end	Day	20% 7% 2 3 3 2 3 3 3 4 48%	1980
November	1st to 10th	Day	15% 6% 2 5% 4 2 3 3 4 6% 50%	1858
	11th to 20th	Day	13% 6% 2 4 3 2 3 3 4 6% 55%	1871
	21st to end	Day	20% 6% 2 4 3 2 3 3 3 5% 49%	1710
December	1st to 10th	Day	19% 7% 2 3 3 2 3 3 4 5% 48%	1710
	11th to 20th	Day	17% 9% 3 5% 4 3 4 3 4 5% 42%	2161
	21st to end	Day	20% 11% 3 5% 5% 3 3 4 4 6% 36%	3135
January	1st to 10th	Night	14% 7% 3 4 4 2 3 3 4 6% 50%	2458
	11th to 20th	Night	15% 7% 3 6% 5% 2 2 3 4 5% 49%	2470
	21st to end	Night	16% 6% 2 4 3 2 3 3 4 4 54%	2600
February	1st to 10th	Night	19% 9% 3 5% 4 1 3 4 4 4 44%	2340
	11th to 20th	Night	18% 9% 4 5% 4 2 3 3 4 5% 43%	2196
	21st to end	Night	20% 7% 2 5% 3 2 3 3 4 6% 45%	1655
March	1st to 10th	Night	19% 7% 3 5% 4 2 3 3 5% 5% 44%	1980
	11th to 20th	Night	18% 8% 3 4 5% 3 3 3 4 5% 43%	1980
	21st to end	Night	15% 8% 3 6% 5% 2 4 3 5% 6% 44%	2178
April	1st to 10th	Night	13% 6% 3 4 4 3 4 3 5% 6% 48%	1933
	11th to 20th	Night	14% 7% 2 5% 4 2 4 3 4 6% 49%	1775
	21st to end	Night	14% 7% 3 5% 5% 3 3 4 5% 7% 46%	1798
May	1st to 10th	Night	12% 7% 3 4 5% 2 4 4 5% 7% 47%	1620
	11th to 20th	Night	13% 5% 2 4 4 3 5% 5% 6% 8% 45%	1593
	21st to end	Night	11% 6% 3 6% 4 3 4 4 6% 9% 44%	1745
June	1st to 10th	Night	5% 5% 1 4 4 2 3 5% 6% 7% 56%	1620
	11th to 20th	Night	6% 4 2 4 4 1 3 4 5% 9% 58%	1620
	21st to end	Night	5% 4 2 2 2 2 3 3 5% 9% 64%	1620
July	1st to 10th	Night	5% 4 2 5% 5% 4 5% 6% 8% 11% 46%	1620
	11th to 20th	Night	3 2 1 2 3 2 4 4 5% 10% 63%	1620
	21st to end	Night	4 3 1 3 3 3 5% 5% 7% 11% 55%	1772
August	1st to 10th	Night	3 2 1 3 4 3 5% 5% 7% 10% 58%	1611
	11th to 20th	Night	7% 3 2 4 5% 2 4 5% 7% 10% 51%	1618
	21st to end	Night	5% 4 2 5% 5% 3 4 4 4 11% 53%	1980
September	1st to 10th	Night	6% 5% 2 3 4 2 4 4 6% 7% 57%	1854
	11th to 20th	Night	9% 4 2 4 5% 3 4 5% 6% 8% 50%	1980
	21st to end	Night	9% 4 1 3 3 2 3 4 4 5% 61%	1980
October	1st to 10th	Night	9% 4 2 3 3 2 4 4 5% 7% 57%	2124
	11th to 20th	Night	15% 4 2 4 3 1 3 3 4 5% 59%	2160
	21st to end	Night	18% 6% 2 4 3 2 2 2 3 3 54%	2376
November	1st to 10th	Night	11% 6% 2 3 3 2 3 3 3 6% 57%	2220
	11th to 20th	Night	10% 6% 3 4 3 3 3 4 4 5% 57%	2306
	21st to end	Night	17% 8% 3 4 3 2 3 2 4 6% 48%	2470
December	1st to 10th	Night	17% 6% 2 4 4 3 3 3 4 5% 48%	2470
	11th to 20th	Night	16% 7% 3 5% 5% 3 3 3 4 3 46%	3036
	21st to end	Night	18% 9% 3 5% 5% 3 4 3 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	39% 3 7% 24% 20% 7%	1708
	11th to 20th	Day	39% 4 8% 24% 22% 3	1710
	21st to end	Day	40% 3 5% 22% 24% 6%	1791
February	1st to 10th	Day	50% 2 9% 15% 20% 4	1620
	11th to 20th	Day	49% 4 6% 18% 19% 5%	1676
	21st to end	Day	49% 3 5% 14% 20% 8%	1601
March	1st to 10th	Day	44% 3 7% 16% 19% 11%	1980
	11th to 20th	Day	50% 4 7% 18% 16% 5%	1980
	21st to end	Day	49% 4 8% 21% 15% 3	2178
April	1st to 10th	Day	44% 4 9% 19% 19% 5%	2025
	11th to 20th	Day	45% 5% 8% 21% 18% 4	2134
	21st to end	Day	48% 6% 7% 19% 18% 3	2160
May	1st to 10th	Day	45% 5% 9% 21% 17% 3	2338
	11th to 20th	Day	44% 8% 12% 22% 14% 1	2306
	21st to end	Day	47% 7% 11% 22% 13%	2531
June	1st to 10th	Day	37% 8% 13% 26% 14% 2	2340
	11th to 20th	Day	39% 8% 12% 22% 17% 1	2340
	21st to end	Day	30% 7% 13% 28% 20% 3	2340
July	1st to 10th	Day	39% 10% 17% 22% 11% 1	2276
	11th to 20th	Day	29% 8% 13% 28% 21% 1	2271
	21st to end	Day	32% 11% 16% 29% 12% 1	2405
August	1st to 10th	Day	32% 9% 15% 29% 15% 1	2314
	11th to 20th	Day	36% 8% 14% 25% 16% 2	2280
	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	36% 5% 7% 18% 27% 7%	2458
	11th to 20th	Night	39% 4 9% 20% 23% 6%	2470
	21st to end	Night	35% 3 4 20% 28% 9%	2600
February	1st to 10th	Night	44% 4 9% 19% 18% 7%	2340
	11th to 20th	Night	45% 3 5% 21% 20% 6%	2197
	21st to end	Night	41% 4 8% 16% 21% 10%	1655
March	1st to 10th	Night	43% 3 6% 15% 20% 12%	1980
	11th to 20th	Night	44% 5% 7% 17% 19% 7%	1980
	21st to end	Night	42% 5% 8% 21% 20% 4	2178
April	1st to 10th	Night	38% 4 9% 20% 19% 9%	1933
	11th to 20th	Night	37% 4 8% 22% 20% 9%	1775
	21st to end	Night	37% 6% 9% 23% 23% 2	1798
May	1st to 10th	Night	37% 6% 10% 22% 17% 7%	1620
	11th to 20th	Night	36% 7% 15% 26% 14% 2	1594
	21st to end	Night	37% 7% 13% 27% 14% 2	1746
June	1st to 10th	Night	25% 7% 16% 29% 20% 3	1620
	11th to 20th	Night	25% 6% 11% 33% 22% 3	1620
	21st to end	Night	20% 5% 13% 29% 29% 5%	1620
July	1st to 10th	Night	28% 8% 20% 26% 16% 2	1575
	11th to 20th	Night	16% 7% 16% 34% 25% 3	1566
	21st to end	Night	20% 8% 16% 36% 18% 1	1673
August	1st to 10th	Night	20% 9% 16% 32% 20% 3	1601
	11th to 20th	Night	26% 7% 15% 29% 21% 2	1618
	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	25% 27% 32% 12% 3	267
February	1st to 10th	Day	34% 19% 31% 10% 5%	240
	11th to 20th	Day	38% 26% 29% 5% 1	240
	21st to end	Day	41% 25% 23% 9% 2	198
March	1st to 10th	Day	35% 21% 30% 13% 1	240
	11th to 20th	Day	42% 21% 23% 10% 3	240
	21st to end	Day	31% 23% 37% 7% 2	264
April	1st to 10th	Day	28% 19% 35% 12% 6%	285
	11th to 20th	Day	32% 16% 30% 14% 7%	412
	21st to end	Day	26% 20% 29% 18% 6% 1	420
May	1st to 10th	Day	23% 16% 37% 19% 4 1	601
	11th to 20th	Day	20% 12% 34% 24% 9% 2	625
	21st to end	Day	16% 9% 36% 20% 17% 3	679
June	1st to 10th	Day	12% 7% 21% 32% 22% 6%	630
	11th to 20th	Day	10% 4 29% 35% 17% 4	630
	21st to end	Day	6% 5% 26% 34% 20% 9%	630
July	1st to 10th	Day	8% 3 17% 34% 30% 8%	621
	11th to 20th	Day	4 1 15% 36% 33% 10%	618
	21st to end	Day	5% 2 11% 36% 35% 11%	684
August	1st to 10th	Day	6% 3 14% 40% 31% 5%	626
	11th to 20th	Day	11% 3 14% 37% 29% 6%	594
	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% 18% 29% 23% 5% 1	950
	21st to end	Night	21% 17% 30% 28% 5%	1000
February	1st to 10th	Night	26% 18% 27% 24% 5%	900
	11th to 20th	Night	26% 21% 29% 21% 2	802
	21st to end	Night	29% 17% 31% 19% 4	471
March	1st to 10th	Night	25% 14% 26% 30% 5%	540
	11th to 20th	Night	24% 14% 29% 28% 5% 1	540
	21st to end	Night	21% 19% 33% 21% 6% 1	594
April	1st to 10th	Night	17% 19% 32% 26% 6%	540
	11th to 20th	Night	20% 16% 27% 28% 9%	533
	21st to end	Night	19% 16% 33% 21% 10% 1	540
May	1st to 10th	Night	16% 10% 32% 32% 10%	540
	11th to 20th	Night	15% 8% 30% 28% 17% 2	531
	21st to end	Night	14% 5% 29% 28% 22% 2	584
June	1st to 10th	Night	7% 4 16% 35% 35% 3	540
	11th to 20th	Night	8% 3 22% 39% 28% 1	540
	21st to end	Night	5% 2 19% 34% 34% 6%	540
July	1st to 10th	Night	4 2 10% 31% 47% 6%	525
	11th to 20th	Night	4 1 10% 31% 47% 7%	522
	21st to end	Night	4 1 7% 33% 48% 8%	591
August	1st to 10th	Night	3 1 9% 37% 45% 5%	537
	11th to 20th	Night	9% 2 7% 37% 38% 7%	534
	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 2024-01-19 08:28:32. Version ac07

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