Pixie Land
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pixie Land clear sky chart from 2005-11-06 to 2024-01-14.

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	9% 7% 3 6% 5% 3 4 5% 5% 7% 46%	74777
	Night	11% 8% 3 6% 5% 3 4 4 5% 7% 43%	74995
Transparency	Day	37% 8% 13% 22% 16% 5%	74480
	Night	41% 8% 14% 21% 12% 3	74813
Seeing	Day	14% 16% 29% 23% 14% 4	13396
	Night	14% 11% 26% 31% 17% 2	22535

By Month

Percentage Cloud Cover SW (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	22% 17% 6% 11% 7% 6% 5% 4 4 4 12%	1519
	11th to 20th	Day	17% 14% 7% 11% 9% 4 6% 5% 6% 5% 14%	1464
	21st to end	Day	16% 13% 7% 12% 7% 4 6% 6% 6% 6% 17%	1629
February	1st to 10th	Day	15% 13% 5% 9% 6% 3 5% 6% 5% 8% 24%	1620
	11th to 20th	Day	14% 8% 3 7% 5% 4 6% 6% 7% 6% 32%	1575
	21st to end	Day	12% 8% 4 7% 8% 4 6% 6% 7% 8% 29%	1473
March	1st to 10th	Day	13% 9% 4 7% 6% 4 7% 6% 8% 9% 27%	1800
	11th to 20th	Day	13% 9% 3 9% 8% 3 5% 6% 7% 9% 28%	1966
	21st to end	Day	11% 9% 4 7% 8% 4 6% 7% 8% 7% 28%	2292
April	1st to 10th	Day	9% 7% 3 8% 6% 4 6% 6% 7% 9% 35%	2160
	11th to 20th	Day	9% 8% 3 6% 5% 4 7% 5% 7% 8% 39%	2129
	21st to end	Day	5% 4 2 5% 5% 3 6% 6% 7% 10% 46%	2295
May	1st to 10th	Day	6% 4 2 5% 4 3 5% 5% 7% 8% 52%	2520
	11th to 20th	Day	9% 6% 2 5% 5% 3 5% 5% 8% 10% 42%	2477
	21st to end	Day	8% 5% 2 4 5% 3 5% 5% 6% 8% 48%	2723
June	1st to 10th	Day	9% 4 2 5% 5% 3 5% 5% 6% 8% 48%	2520
	11th to 20th	Day	4 3 2 4 5% 3 4 5% 6% 9% 55%	2520
	21st to end	Day	3 2 2 3 3 2 3 3 4 6% 69%	2520
July	1st to 10th	Day	1 1 1 2 2 1 3 3 4 5% 78%	2520
	11th to 20th	Day	3 1 1 2 2 1 2 3 4 4 77%	2520
	21st to end	Day	2 1 1 1 1 1 2 3 3 85%	2741
August	1st to 10th	Day	2 2 1 2 2 1 2 2 3 5% 78%	2477
	11th to 20th	Day	2 1 1 2 2 1 2 3 3 5% 78%	2298
	21st to end	Day	3 2 1 3 3 2 3 4 3 6% 71%	2381
September	1st to 10th	Day	2 2 1 2 2 2 3 3 3 6% 75%	2160
	11th to 20th	Day	4 3 2 3 4 3 4 4 4 7% 61%	2160
	21st to end	Day	8% 4 2 4 4 3 4 4 5% 6% 56%	1931
October	1st to 10th	Day	9% 5% 2 5% 5% 3 4 4 6% 8% 51%	1800
	11th to 20th	Day	10% 4 3 7% 5% 3 4 5% 8% 7% 43%	1800
	21st to end	Day	15% 7% 4 6% 6% 4 6% 5% 5% 6% 37%	1850
November	1st to 10th	Day	14% 10% 4 8% 7% 4 5% 6% 7% 8% 26%	1655
	11th to 20th	Day	16% 12% 6% 10% 7% 5% 4 7% 6% 7% 20%	1520
	21st to end	Day	16% 11% 4 10% 8% 3 6% 5% 6% 6% 26%	1520
December	1st to 10th	Day	17% 13% 7% 10% 6% 3 4 5% 4 5% 26%	1520
	11th to 20th	Day	19% 17% 9% 15% 7% 4 4 4 4 5% 11%	1928
	21st to end	Day	22% 18% 8% 11% 8% 4 4 4 4 5% 12%	2794
January	1st to 10th	Night	20% 15% 6% 10% 8% 4 4 5% 5% 6% 17%	2646
	11th to 20th	Night	21% 14% 5% 10% 7% 3 5% 4 4 7% 21%	2568
	21st to end	Night	16% 11% 5% 11% 7% 4 5% 5% 5% 7% 24%	2723
February	1st to 10th	Night	15% 12% 5% 7% 6% 3 5% 5% 6% 7% 30%	2340
	11th to 20th	Night	12% 9% 4 6% 6% 3 5% 4 5% 7% 38%	2272
	21st to end	Night	12% 11% 4 9% 7% 3 5% 5% 6% 7% 32%	1781
March	1st to 10th	Night	13% 9% 3 6% 6% 4 6% 6% 6% 8% 32%	2160
	11th to 20th	Night	11% 6% 3 6% 6% 4 6% 7% 8% 8% 34%	1991
	21st to end	Night	10% 8% 4 6% 6% 5% 6% 6% 6% 8% 33%	2063
April	1st to 10th	Night	10% 7% 3 7% 6% 3 6% 5% 6% 9% 39%	1800
	11th to 20th	Night	9% 6% 3 4 5% 2 5% 5% 6% 8% 48%	1779
	21st to end	Night	7% 4 2 4 5% 4 5% 5% 6% 10% 48%	1661
May	1st to 10th	Night	5% 4 2 4 5% 3 4 5% 6% 7% 56%	1440
	11th to 20th	Night	7% 3 2 4 4 3 5% 5% 7% 11% 50%	1416
	21st to end	Night	5% 5% 2 5% 4 2 5% 6% 8% 9% 49%	1552
June	1st to 10th	Night	9% 5% 2 4 4 3 5% 4 6% 8% 49%	1440
	11th to 20th	Night	6% 3 1 3 3 2 4 4 5% 9% 60%	1440
	21st to end	Night	2 3 1 3 4 2 4 4 3 5% 69%	1440
July	1st to 10th	Night	2 1 1 3 2 2 2 3 3 5% 78%	1440
	11th to 20th	Night	1 1 1 2 2 1 3 3 3 4 79%	1440
	21st to end	Night	1 1 1 1 1 1 2 3 3 85%	1576
August	1st to 10th	Night	2 2 1 2 3 1 2 3 3 5% 77%	1459
	11th to 20th	Night	3 1 1 2 2 2 2 2 3 4 78%	1602
	21st to end	Night	2 2 1 2 2 1 2 3 4 5% 75%	1975
September	1st to 10th	Night	2 2 1 2 2 1 2 3 4 5% 77%	1800
	11th to 20th	Night	4 3 2 3 4 3 4 4 4 6% 65%	1800
	21st to end	Night	6% 3 1 3 4 3 3 4 5% 7% 60%	2026
October	1st to 10th	Night	8% 5% 3 5% 4 2 3 4 4 6% 56%	2160
	11th to 20th	Night	11% 4 2 5% 6% 3 4 4 5% 7% 48%	2160
	21st to end	Night	12% 6% 3 5% 5% 3 4 5% 4 7% 45%	2506
November	1st to 10th	Night	17% 6% 3 7% 6% 3 6% 5% 6% 7% 34%	2421
	11th to 20th	Night	19% 9% 5% 7% 5% 4 5% 5% 6% 7% 28%	2660
	21st to end	Night	14% 9% 5% 7% 7% 4 5% 5% 6% 7% 33%	2660
December	1st to 10th	Night	17% 12% 7% 9% 7% 3 5% 4 5% 6% 27%	2660
	11th to 20th	Night	22% 14% 7% 12% 8% 4 5% 4 4 5% 14%	3276
	21st to end	Night	20% 15% 6% 11% 6% 3 4 4 4 5% 22%	4862

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	75% 8% 9% 8% 1	1519
	11th to 20th	Day	70% 9% 13% 7% 2	1464
	21st to end	Day	65% 12% 11% 9% 3	1629
February	1st to 10th	Day	59% 11% 17% 11% 2	1620
	11th to 20th	Day	49% 12% 16% 17% 6%	1584
	21st to end	Day	50% 11% 16% 15% 8%	1473
March	1st to 10th	Day	48% 12% 15% 16% 7%	1800
	11th to 20th	Day	50% 8% 13% 24% 4	1966
	21st to end	Day	49% 12% 16% 18% 4	2292
April	1st to 10th	Day	42% 10% 17% 21% 10%	2160
	11th to 20th	Day	40% 9% 19% 18% 12% 2	2132
	21st to end	Day	30% 10% 20% 25% 14% 2	2295
May	1st to 10th	Day	27% 9% 17% 28% 17% 2	2520
	11th to 20th	Day	35% 8% 15% 26% 15% 2	2480
	21st to end	Day	31% 9% 19% 28% 12% 1	2724
June	1st to 10th	Day	32% 7% 14% 31% 14% 3	2520
	11th to 20th	Day	24% 7% 16% 36% 15% 2	2520
	21st to end	Day	17% 4 14% 33% 23% 9%	2520
July	1st to 10th	Day	10% 4 11% 28% 32% 16%	2451
	11th to 20th	Day	11% 3 8% 20% 36% 22%	2445
	21st to end	Day	7% 2 6% 20% 43% 23%	2589
August	1st to 10th	Day	11% 3 10% 27% 34% 15%	2460
	11th to 20th	Day	10% 3 9% 28% 34% 14%	2298
	21st to end	Day	15% 4 9% 31% 34% 7%	2381
September	1st to 10th	Day	13% 3 9% 32% 29% 14%	2160
	11th to 20th	Day	23% 6% 14% 26% 24% 7%	2160
	21st to end	Day	28% 6% 15% 27% 18% 5%	1931
October	1st to 10th	Day	32% 7% 15% 28% 16% 3	1800
	11th to 20th	Day	37% 8% 18% 22% 13% 1	1800
	21st to end	Day	46% 10% 15% 20% 9%	1850
November	1st to 10th	Day	52% 11% 14% 17% 5% 1	1655
	11th to 20th	Day	61% 11% 13% 12% 2 1	1520
	21st to end	Day	57% 9% 16% 11% 6% 1	1520
December	1st to 10th	Day	60% 9% 13% 14% 4	1520
	11th to 20th	Day	75% 8% 9% 5% 2	1928
	21st to end	Day	74% 9% 8% 8% 1	2794
January	1st to 10th	Night	70% 10% 11% 8% 2	2646
	11th to 20th	Night	64% 9% 13% 9% 3	2568
	21st to end	Night	59% 11% 15% 13% 2 1	2723
February	1st to 10th	Night	53% 10% 19% 14% 3	2340
	11th to 20th	Night	45% 10% 18% 20% 7% 1	2274
	21st to end	Night	49% 10% 15% 19% 6% 1	1781
March	1st to 10th	Night	48% 9% 18% 17% 7% 1	2160
	11th to 20th	Night	43% 10% 18% 21% 7%	1991
	21st to end	Night	46% 11% 19% 19% 5%	2063
April	1st to 10th	Night	40% 10% 18% 22% 8% 1	1800
	11th to 20th	Night	34% 8% 19% 25% 11% 3	1779
	21st to end	Night	32% 11% 17% 27% 11% 2	1661
May	1st to 10th	Night	25% 7% 17% 35% 14% 1	1440
	11th to 20th	Night	28% 8% 22% 28% 12% 3	1416
	21st to end	Night	28% 10% 25% 26% 11% 1	1552
June	1st to 10th	Night	32% 8% 15% 33% 10% 2	1440
	11th to 20th	Night	22% 6% 18% 39% 14% 1	1440
	21st to end	Night	19% 4 12% 35% 24% 7%	1440
July	1st to 10th	Night	12% 3 13% 27% 30% 15%	1400
	11th to 20th	Night	10% 4 10% 23% 34% 20%	1392
	21st to end	Night	6% 2 5% 20% 44% 23%	1488
August	1st to 10th	Night	12% 3 8% 29% 34% 14%	1451
	11th to 20th	Night	12% 3 9% 29% 34% 13%	1602
	21st to end	Night	12% 4 11% 30% 35% 9%	1975
September	1st to 10th	Night	11% 4 13% 30% 29% 15%	1800
	11th to 20th	Night	21% 6% 12% 29% 20% 12%	1800
	21st to end	Night	22% 7% 15% 29% 21% 7%	2026
October	1st to 10th	Night	30% 6% 13% 24% 25% 2	2160
	11th to 20th	Night	35% 8% 14% 26% 15% 2	2160
	21st to end	Night	37% 9% 14% 23% 15% 1	2506
November	1st to 10th	Night	47% 10% 15% 22% 7%	2421
	11th to 20th	Night	55% 12% 13% 16% 4	2660
	21st to end	Night	51% 11% 17% 16% 6%	2660
December	1st to 10th	Night	60% 10% 13% 14% 3	2660
	11th to 20th	Night	71% 12% 10% 6% 1	3276
	21st to end	Night	67% 9% 10% 11% 4	4862

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	29% 18% 21% 19% 11% 2	180
	11th to 20th	Day	28% 12% 25% 24% 10% 1	166
	21st to end	Day	27% 7% 25% 25% 14% 1	221
February	1st to 10th	Day	24% 16% 27% 23% 9% 1	340
	11th to 20th	Day	28% 18% 25% 21% 8%	335
	21st to end	Day	20% 21% 27% 23% 7% 2	344
March	1st to 10th	Day	20% 20% 28% 21% 8% 2	420
	11th to 20th	Day	18% 20% 25% 25% 11% 1	420
	21st to end	Day	20% 21% 30% 18% 9% 1	462
April	1st to 10th	Day	24% 19% 30% 16% 9% 2	420
	11th to 20th	Day	17% 28% 29% 15% 8% 3	412
	21st to end	Day	15% 24% 31% 20% 8% 2	420
May	1st to 10th	Day	13% 20% 31% 23% 11% 3	423
	11th to 20th	Day	18% 14% 30% 21% 13% 4	448
	21st to end	Day	12% 16% 31% 25% 12% 4	485
June	1st to 10th	Day	11% 23% 28% 21% 14% 4	450
	11th to 20th	Day	12% 26% 33% 19% 8% 2	450
	21st to end	Day	6% 15% 32% 28% 15% 4	450
July	1st to 10th	Day	3 11% 44% 27% 13% 2	446
	11th to 20th	Day	6% 13% 35% 29% 15% 2	444
	21st to end	Day	2 9% 34% 27% 21% 8%	487
August	1st to 10th	Day	5% 7% 32% 23% 22% 11%	447
	11th to 20th	Day	3 8% 24% 31% 26% 9%	437
	21st to end	Day	6% 12% 31% 23% 21% 7%	495
September	1st to 10th	Day	4 12% 26% 29% 21% 7%	450
	11th to 20th	Day	8% 11% 30% 24% 23% 5%	450
	21st to end	Day	9% 16% 25% 27% 19% 4	450
October	1st to 10th	Day	11% 15% 29% 22% 17% 6%	450
	11th to 20th	Day	13% 16% 22% 25% 18% 6%	450
	21st to end	Day	19% 16% 25% 22% 13% 5%	365
November	1st to 10th	Day	20% 13% 29% 25% 10% 3	261
	11th to 20th	Day	23% 18% 21% 23% 12% 3	180
	21st to end	Day	22% 11% 23% 27% 16% 2	180
December	1st to 10th	Day	24% 12% 21% 25% 11% 7%	180
	11th to 20th	Day	27% 11% 32% 22% 9% 1	180
	21st to end	Day	22% 15% 27% 23% 12% 1	198
January	1st to 10th	Night	26% 11% 24% 27% 11% 1	760
	11th to 20th	Night	25% 7% 22% 28% 15% 2	734
	21st to end	Night	21% 8% 20% 32% 17% 2	792
February	1st to 10th	Night	21% 13% 23% 29% 14% 1	720
	11th to 20th	Night	17% 13% 23% 32% 15% 1	704
	21st to end	Night	18% 16% 23% 32% 11% 1	592
March	1st to 10th	Night	17% 11% 26% 30% 15% 1	720
	11th to 20th	Night	13% 11% 27% 35% 13% 1	720
	21st to end	Night	14% 17% 31% 26% 10% 1	792
April	1st to 10th	Night	15% 15% 28% 27% 13% 1	720
	11th to 20th	Night	13% 18% 30% 24% 13% 2	711
	21st to end	Night	9% 17% 36% 24% 13% 1	581
May	1st to 10th	Night	8% 14% 33% 28% 16% 1	360
	11th to 20th	Night	10% 10% 27% 33% 18% 2	354
	21st to end	Night	7% 8% 32% 38% 12% 4	389
June	1st to 10th	Night	11% 15% 32% 28% 14% 1	360
	11th to 20th	Night	9% 19% 38% 26% 8%	360
	21st to end	Night	4 13% 31% 33% 17% 1	360
July	1st to 10th	Night	3 9% 32% 37% 17% 1	350
	11th to 20th	Night	1 8% 43% 34% 12% 2	348
	21st to end	Night	2 8% 28% 39% 22% 2	394
August	1st to 10th	Night	2 6% 28% 37% 24% 3	385
	11th to 20th	Night	3 4 20% 32% 29% 11%	534
	21st to end	Night	3 10% 30% 32% 22% 4	787
September	1st to 10th	Night	3 7% 26% 33% 29% 3	720
	11th to 20th	Night	5% 5% 26% 28% 30% 6%	720
	21st to end	Night	7% 8% 22% 31% 28% 4	720
October	1st to 10th	Night	11% 8% 22% 37% 20% 4	720
	11th to 20th	Night	13% 8% 20% 30% 25% 3	720
	21st to end	Night	16% 10% 24% 30% 17% 3	792
November	1st to 10th	Night	18% 9% 23% 36% 13%	740
	11th to 20th	Night	24% 9% 24% 28% 13% 1	760
	21st to end	Night	15% 10% 24% 33% 15% 3	760
December	1st to 10th	Night	20% 9% 24% 29% 16% 2	760
	11th to 20th	Night	25% 8% 22% 31% 13% 1	760
	21st to end	Night	25% 12% 24% 29% 9% 1	836

Page generated at 2024-01-11 01:22:40. Version ac07

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