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 2024-11-25.

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	8% 7% 2 6% 4 4 4 4 5% 6% 49%	105539
	Night	11% 8% 3 6% 4 4 4 3 5% 6% 45%	102614
Transparency	Day	34% 7% 13% 22% 16% 8%	105282
	Night	38% 8% 14% 22% 13% 5%	102460
Seeing	Day	14% 16% 29% 24% 14% 4	14558
	Night	14% 11% 26% 31% 16% 2	23578

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	21% 18% 5% 13% 6% 6% 5% 3 5% 5% 13%	2539
	11th to 20th	Day	21% 19% 6% 10% 6% 5% 5% 3 7% 5% 14%	2540
	21st to end	Day	27% 16% 6% 14% 6% 5% 4 3 4 4 10%	2867
February	1st to 10th	Day	14% 14% 4 10% 5% 5% 6% 5% 6% 7% 24%	1710
	11th to 20th	Day	14% 10% 3 8% 5% 6% 6% 5% 7% 6% 31%	1665
	21st to end	Day	11% 10% 3 8% 7% 5% 6% 4 7% 8% 29%	1562
March	1st to 10th	Day	9% 10% 3 7% 6% 6% 6% 5% 8% 10% 31%	3138
	11th to 20th	Day	9% 7% 2 7% 5% 3 4 4 5% 7% 49%	3476
	21st to end	Day	9% 10% 3 9% 7% 6% 6% 5% 7% 8% 30%	4029
April	1st to 10th	Day	9% 8% 3 8% 5% 6% 6% 5% 7% 9% 35%	2280
	11th to 20th	Day	9% 8% 2 7% 5% 5% 6% 5% 7% 8% 39%	2249
	21st to end	Day	5% 5% 2 6% 5% 5% 5% 5% 7% 9% 46%	2423
May	1st to 10th	Day	9% 5% 1 5% 3 4 4 4 6% 7% 52%	4420
	11th to 20th	Day	5% 3 1 3 3 3 3 3 5% 7% 64%	4377
	21st to end	Day	6% 6% 2 5% 5% 5% 5% 5% 7% 9% 44%	4813
June	1st to 10th	Day	9% 5% 2 6% 4 4 4 4 6% 8% 48%	2660
	11th to 20th	Day	4 4 1 5% 4 4 4 4 6% 9% 55%	2660
	21st to end	Day	3 3 2 3 3 3 3 3 4 6% 68%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 3 4 86%	4420
	11th to 20th	Day	2 1 1 1 1 1 2 2 2 3 84%	4420
	21st to end	Day	1 2 1 2 1 1 1 2 3 3 82%	4790
August	1st to 10th	Day	2 3 1 3 2 2 3 2 3 4 75%	4344
	11th to 20th	Day	1 2 1 3 2 2 3 3 4 7% 72%	4026
	21st to end	Day	4 4 1 4 3 3 3 3 3 5% 68%	4185
September	1st to 10th	Day	2 2 1 3 2 2 2 2 3 6% 74%	2280
	11th to 20th	Day	4 3 1 4 3 4 4 4 5% 7% 60%	2280
	21st to end	Day	7% 4 1 5% 3 3 4 3 5% 6% 58%	2038
October	1st to 10th	Day	5% 3 1 4 3 3 4 3 6% 8% 60%	3180
	11th to 20th	Day	6% 4 3 8% 5% 5% 5% 6% 8% 8% 43%	3161
	21st to end	Day	10% 6% 3 7% 6% 6% 6% 4 7% 9% 36%	3209
November	1st to 10th	Day	13% 12% 3 9% 5% 6% 5% 5% 7% 8% 26%	1744
	11th to 20th	Day	16% 14% 5% 11% 6% 5% 5% 5% 6% 7% 20%	1600
	21st to end	Day	16% 12% 3 11% 7% 4 5% 4 6% 6% 26%	1552
December	1st to 10th	Day	16% 16% 5% 10% 6% 4 4 4 4 5% 26%	1520
	11th to 20th	Day	19% 18% 8% 17% 6% 5% 4 3 4 5% 11%	1928
	21st to end	Day	22% 19% 7% 13% 6% 5% 4 3 4 5% 12%	2794
January	1st to 10th	Night	20% 17% 6% 11% 6% 4 5% 5% 5% 6% 15%	4406
	11th to 20th	Night	25% 16% 4 9% 5% 4 4 3 6% 6% 19%	4420
	21st to end	Night	26% 14% 5% 13% 6% 5% 4 3 4 5% 15%	4787
February	1st to 10th	Night	15% 14% 4 8% 5% 4 5% 4 6% 6% 30%	2470
	11th to 20th	Night	13% 11% 4 7% 5% 5% 4 3 5% 6% 37%	2402
	21st to end	Night	12% 12% 3 10% 6% 5% 4 4 6% 7% 32%	1890
March	1st to 10th	Night	9% 9% 3 7% 5% 6% 6% 5% 8% 9% 32%	3736
	11th to 20th	Night	8% 5% 2 5% 3 4 4 4 5% 5% 54%	3501
	21st to end	Night	9% 7% 4 7% 6% 6% 6% 5% 8% 10% 32%	3623
April	1st to 10th	Night	10% 7% 3 7% 5% 4 6% 4 7% 9% 39%	1900
	11th to 20th	Night	8% 6% 2 5% 5% 3 5% 4 6% 8% 48%	1879
	21st to end	Night	7% 4 2 5% 5% 5% 4 5% 7% 9% 48%	1752
May	1st to 10th	Night	10% 7% 2 5% 4 3 3 3 5% 5% 55%	2540
	11th to 20th	Night	4 2 1 3 2 3 3 3 5% 7% 67%	2516
	21st to end	Night	3 5% 1 4 3 3 5% 4 7% 8% 57%	2762
June	1st to 10th	Night	9% 6% 2 5% 4 5% 5% 4 7% 7% 49%	1520
	11th to 20th	Night	6% 4 1 3 3 3 3 3 5% 8% 60%	1520
	21st to end	Night	2 3 1 4 3 3 3 3 3 4 69%	1520
July	1st to 10th	Night	1 1 2 1 1 1 1 2 3 87%	2540
	11th to 20th	Night	1 1 1 2 1 2 2 2 3 4 83%	2540
	21st to end	Night	1 1 1 1 1 1 2 3 3 86%	2761
August	1st to 10th	Night	3 2 1 3 2 2 2 2 3 5% 74%	2584
	11th to 20th	Night	2 1 1 2 2 3 3 3 4 6% 73%	2812
	21st to end	Night	2 2 1 3 2 3 3 2 4 6% 73%	3493
September	1st to 10th	Night	2 1 1 2 2 2 3 2 4 5% 76%	1900
	11th to 20th	Night	4 3 1 4 4 3 4 3 4 6% 64%	1900
	21st to end	Night	6% 3 1 3 3 3 3 3 5% 7% 61%	2139
October	1st to 10th	Night	5% 3 1 3 2 2 3 3 5% 7% 65%	3800
	11th to 20th	Night	7% 4 2 6% 4 4 6% 4 7% 9% 47%	3777
	21st to end	Night	9% 6% 2 6% 4 5% 6% 5% 7% 8% 41%	4352
November	1st to 10th	Night	16% 7% 3 8% 5% 4 6% 4 6% 7% 34%	2552
	11th to 20th	Night	19% 11% 4 8% 5% 5% 5% 4 6% 7% 27%	2800
	21st to end	Night	14% 11% 4 8% 6% 5% 5% 4 6% 7% 32%	2722
December	1st to 10th	Night	16% 14% 6% 10% 6% 4 4 4 5% 5% 27%	2660
	11th to 20th	Night	22% 15% 6% 13% 7% 5% 5% 4 4 6% 13%	3276
	21st to end	Night	20% 16% 6% 12% 5% 4 4 3 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	70% 8% 9% 12%	2539
	11th to 20th	Day	69% 8% 15% 7% 1	2540
	21st to end	Day	77% 9% 7% 5% 2	2867
February	1st to 10th	Day	58% 11% 18% 11% 2	1710
	11th to 20th	Day	50% 12% 16% 16% 5%	1674
	21st to end	Day	50% 11% 16% 15% 8%	1562
March	1st to 10th	Day	41% 15% 16% 21% 7%	3138
	11th to 20th	Day	34% 8% 15% 36% 7%	3476
	21st to end	Day	46% 13% 14% 21% 6%	4029
April	1st to 10th	Day	41% 10% 18% 21% 9%	2280
	11th to 20th	Day	39% 9% 19% 18% 13% 3	2252
	21st to end	Day	31% 10% 19% 25% 13% 2	2423
May	1st to 10th	Day	30% 7% 13% 25% 23% 2	4420
	11th to 20th	Day	20% 5% 11% 37% 24% 4	4380
	21st to end	Day	30% 12% 23% 27% 8% 1	4814
June	1st to 10th	Day	32% 7% 13% 30% 14% 3	2660
	11th to 20th	Day	24% 6% 15% 35% 16% 3	2660
	21st to end	Day	17% 4 13% 34% 23% 9%	2660
July	1st to 10th	Day	6% 2 6% 17% 28% 41%	4351
	11th to 20th	Day	8% 2 5% 12% 26% 47%	4345
	21st to end	Day	9% 2 7% 20% 40% 22%	4639
August	1st to 10th	Day	14% 3 6% 17% 35% 25%	4328
	11th to 20th	Day	13% 3 11% 39% 26% 8%	4065
	21st to end	Day	20% 4 11% 25% 33% 7%	4184
September	1st to 10th	Day	13% 3 9% 33% 29% 14%	2280
	11th to 20th	Day	23% 6% 15% 27% 23% 7%	2280
	21st to end	Day	27% 6% 15% 29% 18% 5%	2038
October	1st to 10th	Day	23% 6% 13% 32% 24% 3	3180
	11th to 20th	Day	36% 7% 19% 23% 14% 1	3161
	21st to end	Day	41% 8% 13% 28% 9% 1	3209
November	1st to 10th	Day	52% 11% 15% 17% 4 1	1744
	11th to 20th	Day	61% 11% 13% 13% 2 1	1600
	21st to end	Day	57% 9% 16% 11% 5% 1	1552
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	68% 12% 10% 8% 2	4406
	11th to 20th	Night	64% 10% 16% 9% 2	4420
	21st to end	Night	74% 8% 9% 7% 1	4787
February	1st to 10th	Night	54% 11% 19% 13% 3	2470
	11th to 20th	Night	46% 10% 18% 19% 6% 1	2404
	21st to end	Night	49% 10% 15% 18% 6% 1	1890
March	1st to 10th	Night	41% 14% 17% 23% 5%	3736
	11th to 20th	Night	29% 9% 18% 33% 10%	3501
	21st to end	Night	42% 16% 18% 21% 3	3623
April	1st to 10th	Night	40% 10% 20% 22% 8% 1	1900
	11th to 20th	Night	34% 8% 19% 25% 12% 3	1879
	21st to end	Night	31% 11% 18% 27% 11% 2	1752
May	1st to 10th	Night	29% 7% 12% 29% 22% 1	2540
	11th to 20th	Night	16% 5% 14% 39% 22% 3	2516
	21st to end	Night	20% 12% 34% 28% 6%	2762
June	1st to 10th	Night	33% 8% 14% 32% 10% 3	1520
	11th to 20th	Night	22% 6% 17% 38% 16% 1	1520
	21st to end	Night	18% 4 12% 34% 24% 6%	1520
July	1st to 10th	Night	7% 2 7% 17% 32% 36%	2500
	11th to 20th	Night	8% 3 6% 15% 27% 41%	2492
	21st to end	Night	5% 2 7% 21% 40% 25%	2674
August	1st to 10th	Night	14% 2 5% 19% 36% 23%	2576
	11th to 20th	Night	12% 4 12% 42% 23% 7%	2839
	21st to end	Night	14% 3 14% 29% 30% 10%	3493
September	1st to 10th	Night	11% 3 13% 29% 29% 15%	1900
	11th to 20th	Night	22% 6% 13% 30% 19% 11%	1900
	21st to end	Night	21% 6% 15% 30% 21% 7%	2139
October	1st to 10th	Night	20% 4 12% 33% 29% 2	3800
	11th to 20th	Night	32% 7% 19% 26% 14% 1	3777
	21st to end	Night	37% 8% 14% 29% 12% 1	4352
November	1st to 10th	Night	47% 10% 15% 21% 7%	2552
	11th to 20th	Night	55% 11% 13% 16% 4	2800
	21st to end	Night	51% 10% 16% 15% 6%	2722
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	30% 11% 24% 24% 11% 1	180
	21st to end	Day	27% 8% 26% 25% 13% 1	245
February	1st to 10th	Day	22% 16% 28% 23% 10% 1	370
	11th to 20th	Day	27% 17% 26% 21% 9%	365
	21st to end	Day	20% 21% 27% 23% 8% 2	379
March	1st to 10th	Day	19% 20% 28% 22% 9% 2	460
	11th to 20th	Day	17% 19% 24% 26% 12% 3	460
	21st to end	Day	20% 20% 32% 18% 9% 1	506
April	1st to 10th	Day	22% 20% 31% 16% 9% 2	460
	11th to 20th	Day	16% 27% 31% 15% 9% 3	452
	21st to end	Day	15% 24% 31% 19% 8% 2	460
May	1st to 10th	Day	14% 19% 31% 22% 11% 3	463
	11th to 20th	Day	16% 15% 30% 21% 13% 4	488
	21st to end	Day	12% 16% 31% 25% 12% 3	529
June	1st to 10th	Day	12% 22% 28% 21% 13% 4	490
	11th to 20th	Day	12% 25% 33% 19% 9% 2	490
	21st to end	Day	7% 15% 31% 28% 16% 4	490
July	1st to 10th	Day	3 11% 42% 27% 14% 3	486
	11th to 20th	Day	5% 12% 34% 30% 16% 3	484
	21st to end	Day	2 10% 32% 27% 21% 8%	531
August	1st to 10th	Day	5% 7% 30% 24% 24% 10%	487
	11th to 20th	Day	3 8% 23% 32% 26% 8%	477
	21st to end	Day	7% 12% 29% 22% 21% 8%	539
September	1st to 10th	Day	4 12% 25% 29% 21% 9%	490
	11th to 20th	Day	8% 11% 29% 26% 22% 4	490
	21st to end	Day	9% 16% 24% 27% 19% 5%	490
October	1st to 10th	Day	10% 14% 29% 22% 17% 7%	490
	11th to 20th	Day	13% 16% 22% 25% 18% 6%	490
	21st to end	Day	17% 15% 26% 23% 14% 4	401
November	1st to 10th	Day	20% 13% 28% 24% 11% 3	290
	11th to 20th	Day	23% 18% 23% 23% 11% 3	200
	21st to end	Day	22% 11% 22% 28% 16% 2	188
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% 8% 21% 28% 15% 2	760
	21st to end	Night	21% 9% 20% 32% 17% 2	836
February	1st to 10th	Night	21% 13% 22% 29% 14% 1	760
	11th to 20th	Night	17% 13% 23% 32% 15% 1	744
	21st to end	Night	18% 17% 23% 31% 11%	628
March	1st to 10th	Night	16% 11% 26% 30% 15% 1	760
	11th to 20th	Night	12% 11% 26% 35% 14% 1	760
	21st to end	Night	14% 17% 31% 26% 10% 1	836
April	1st to 10th	Night	15% 16% 28% 27% 13% 1	760
	11th to 20th	Night	12% 19% 30% 25% 13% 2	751
	21st to end	Night	9% 18% 36% 25% 12% 1	612
May	1st to 10th	Night	9% 16% 32% 27% 15% 1	380
	11th to 20th	Night	10% 11% 27% 32% 18% 2	374
	21st to end	Night	7% 9% 33% 37% 12% 3	411
June	1st to 10th	Night	12% 15% 32% 27% 13% 1	380
	11th to 20th	Night	9% 18% 38% 26% 8%	380
	21st to end	Night	4 13% 32% 34% 17% 1	380
July	1st to 10th	Night	3 9% 32% 38% 18% 1	370
	11th to 20th	Night	1 8% 42% 35% 13% 2	368
	21st to end	Night	1 8% 29% 39% 21% 1	416
August	1st to 10th	Night	2 6% 28% 37% 24% 3	407
	11th to 20th	Night	3 4 20% 34% 28% 10%	564
	21st to end	Night	3 10% 29% 32% 22% 4	831
September	1st to 10th	Night	3 7% 25% 34% 29% 3	760
	11th to 20th	Night	5% 5% 28% 28% 28% 5%	760
	21st to end	Night	7% 8% 22% 31% 28% 4	760
October	1st to 10th	Night	10% 7% 22% 37% 20% 3	760
	11th to 20th	Night	13% 8% 21% 31% 25% 3	760
	21st to end	Night	16% 9% 25% 31% 16% 3	836
November	1st to 10th	Night	18% 10% 23% 36% 13%	780
	11th to 20th	Night	24% 10% 24% 28% 12% 1	800
	21st to end	Night	15% 10% 24% 32% 15% 3	778
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 2024-11-22 05:02:30. Version ac07

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