Stockton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stockton clear sky chart from 2005-11-06 to 2024-02-05.

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	7% 4 2 4 3 2 3 3 4 6% 63%	78366
	Night	9% 4 2 4 3 2 3 3 4 6% 60%	80512
Transparency	Day	24% 5% 8% 19% 24% 20%	78082
	Night	26% 5% 9% 20% 22% 18%	80317
Seeing	Day	7% 5% 16% 28% 29% 14%	14216
	Night	9% 3 15% 40% 30% 4	23704

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	19% 12% 4 7% 6% 3 4 3 5% 6% 30%	2553
	11th to 20th	Day	17% 12% 5% 9% 7% 4 5% 3 4 5% 31%	2860
	21st to end	Day	20% 10% 4 7% 6% 3 5% 5% 4 7% 28%	3146
February	1st to 10th	Day	16% 5% 4 6% 5% 3 5% 5% 4 6% 43%	1657
	11th to 20th	Day	13% 5% 2 5% 3 3 5% 3 5% 6% 49%	1698
	21st to end	Day	14% 4 2 5% 4 2 3 3 4 6% 52%	1480
March	1st to 10th	Day	12% 7% 3 6% 5% 3 5% 6% 6% 8% 39%	1876
	11th to 20th	Day	14% 6% 2 5% 4 3 5% 5% 6% 8% 42%	1980
	21st to end	Day	10% 5% 2 4 4 3 4 5% 5% 8% 48%	2250
April	1st to 10th	Day	11% 6% 2 3 4 2 3 4 6% 7% 50%	2160
	11th to 20th	Day	8% 3 1 4 3 2 3 4 5% 6% 61%	2129
	21st to end	Day	6% 3 1 2 2 2 3 3 4 7% 67%	2160
May	1st to 10th	Day	3 2 1 3 3 1 2 3 4 6% 70%	2169
	11th to 20th	Day	3 3 1 2 2 2 2 3 5% 6% 72%	2436
	21st to end	Day	3 2 1 2 2 1 3 3 4 7% 71%	2723
June	1st to 10th	Day	2 3 1 2 2 2 2 3 4 7% 72%	2520
	11th to 20th	Day	1 1 1 2 2 3 5% 85%	2520
	21st to end	Day	1 1 1 1 1 2 1 2 3 87%	2520
July	1st to 10th	Day	1 1 1 1 1 1 2 3 91%	2520
	11th to 20th	Day	1 1 1 1 1 1 2 2 3 87%	2465
	21st to end	Day	1 1 1 1 1 2 2 4 85%	2546
August	1st to 10th	Day	1 1 1 2 2 1 2 2 2 2 85%	2328
	11th to 20th	Day	1 1 1 1 1 1 1 2 4 87%	2144
	21st to end	Day	1 1 1 1 1 1 2 2 3 89%	2376
September	1st to 10th	Day	1 1 1 1 1 1 2 2 2 89%	2160
	11th to 20th	Day	1 1 1 1 2 1 2 2 3 5% 80%	2160
	21st to end	Day	2 2 1 2 2 1 2 2 3 4 81%	1941
October	1st to 10th	Day	2 1 1 2 2 2 2 3 3 6% 76%	1800
	11th to 20th	Day	4 2 1 2 2 2 3 4 5% 5% 71%	1800
	21st to end	Day	5% 3 2 3 4 2 3 3 4 5% 67%	1980
November	1st to 10th	Day	6% 4 2 3 4 3 3 5% 5% 7% 56%	1747
	11th to 20th	Day	9% 6% 3 4 5% 3 4 4 5% 7% 50%	1710
	21st to end	Day	11% 6% 3 4 4 2 4 3 5% 8% 50%	1610
December	1st to 10th	Day	13% 7% 3 7% 6% 2 3 4 5% 8% 43%	1520
	11th to 20th	Day	23% 10% 4 8% 6% 3 4 4 4 5% 28%	1928
	21st to end	Day	14% 8% 4 8% 6% 4 6% 6% 6% 8% 30%	2794
January	1st to 10th	Night	13% 7% 3 7% 6% 3 5% 4 5% 6% 42%	4377
	11th to 20th	Night	20% 8% 3 7% 6% 3 5% 4 5% 6% 32%	4110
	21st to end	Night	19% 8% 3 6% 6% 3 5% 4 5% 7% 34%	4521
February	1st to 10th	Night	16% 5% 2 5% 3 2 3 3 3 6% 51%	2397
	11th to 20th	Night	11% 4 2 4 3 2 3 4 6% 8% 54%	2148
	21st to end	Night	13% 4 2 3 3 2 4 3 5% 6% 55%	1776
March	1st to 10th	Night	14% 6% 3 6% 5% 2 4 5% 5% 6% 44%	2080
	11th to 20th	Night	12% 6% 2 4 4 3 4 4 4 6% 50%	1980
	21st to end	Night	12% 5% 2 3 3 2 4 4 4 5% 55%	2104
April	1st to 10th	Night	10% 4 2 4 3 3 4 4 5% 7% 54%	1800
	11th to 20th	Night	7% 3 1 3 4 2 3 4 4 6% 62%	1779
	21st to end	Night	5% 2 1 3 2 2 3 4 4 8% 68%	1800
May	1st to 10th	Night	3 2 1 3 2 2 3 4 4 6% 71%	1787
	11th to 20th	Night	3 1 1 2 1 1 2 2 4 6% 76%	1452
	21st to end	Night	2 2 1 2 2 1 2 3 3 6% 77%	1552
June	1st to 10th	Night	3 2 1 2 2 2 3 3 4 5% 75%	1440
	11th to 20th	Night	1 1 1 1 1 2 2 4 87%	1440
	21st to end	Night	1 1 1 1 1 2 1 2 3 87%	1440
July	1st to 10th	Night	1 1 1 1 1 2 2 91%	1440
	11th to 20th	Night	1 1 1 1 1 1 2 2 3 88%	1491
	21st to end	Night	1 1 1 2 2 1 2 2 3 4 82%	1773
August	1st to 10th	Night	1 1 1 1 1 1 2 2 3 84%	1611
	11th to 20th	Night	1 1 1 1 1 1 2 2 3 4 85%	1756
	21st to end	Night	1 1 1 1 1 1 1 2 3 90%	1980
September	1st to 10th	Night	1 1 1 1 1 1 2 3 90%	1800
	11th to 20th	Night	2 1 1 1 1 1 1 2 2 3 84%	1800
	21st to end	Night	2 1 1 1 1 2 2 3 4 84%	2015
October	1st to 10th	Night	4 2 1 1 2 1 2 3 3 5% 75%	2160
	11th to 20th	Night	3 2 1 2 2 1 2 2 4 5% 75%	2160
	21st to end	Night	4 2 1 2 2 2 2 3 4 5% 74%	2376
November	1st to 10th	Night	8% 4 1 3 3 1 2 3 5% 8% 63%	2330
	11th to 20th	Night	8% 4 2 3 4 2 3 4 5% 7% 58%	2470
	21st to end	Night	10% 4 2 3 3 2 4 4 4 6% 59%	2569
December	1st to 10th	Night	14% 5% 2 5% 4 2 3 4 5% 7% 50%	2660
	11th to 20th	Night	19% 8% 3 7% 6% 3 4 5% 6% 7% 34%	3276
	21st to end	Night	16% 7% 3 7% 6% 4 5% 5% 6% 7% 33%	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	52% 9% 12% 20% 7% 1	2553
	11th to 20th	Day	55% 8% 8% 14% 11% 4	2860
	21st to end	Day	54% 9% 10% 15% 10% 2	3146
February	1st to 10th	Day	43% 5% 9% 22% 15% 6%	1657
	11th to 20th	Day	35% 4 12% 23% 21% 5%	1708
	21st to end	Day	35% 5% 9% 24% 22% 5%	1480
March	1st to 10th	Day	41% 6% 11% 22% 16% 4	1876
	11th to 20th	Day	39% 6% 10% 23% 17% 4	1980
	21st to end	Day	33% 8% 14% 21% 19% 5%	2250
April	1st to 10th	Day	33% 5% 12% 24% 18% 7%	2160
	11th to 20th	Day	24% 5% 12% 27% 25% 7%	2132
	21st to end	Day	18% 4 11% 30% 29% 7%	2160
May	1st to 10th	Day	17% 3 10% 26% 33% 11%	2169
	11th to 20th	Day	15% 3 7% 30% 32% 13%	2439
	21st to end	Day	14% 4 15% 30% 27% 10%	2724
June	1st to 10th	Day	14% 4 10% 26% 30% 16%	2520
	11th to 20th	Day	5% 2 6% 22% 35% 29%	2520
	21st to end	Day	7% 2 2 11% 34% 45%	2520
July	1st to 10th	Day	3 1 2 9% 24% 61%	2451
	11th to 20th	Day	6% 2 3 10% 24% 55%	2390
	21st to end	Day	5% 2 2 7% 28% 55%	2405
August	1st to 10th	Day	9% 1 3 10% 31% 47%	2312
	11th to 20th	Day	5% 1 2 10% 34% 47%	2144
	21st to end	Day	5% 1 2 12% 33% 47%	2376
September	1st to 10th	Day	4 1 3 9% 29% 53%	2160
	11th to 20th	Day	9% 2 5% 21% 40% 23%	2160
	21st to end	Day	10% 2 4 18% 38% 28%	1941
October	1st to 10th	Day	12% 3 8% 18% 29% 30%	1800
	11th to 20th	Day	15% 4 8% 23% 27% 24%	1800
	21st to end	Day	20% 4 8% 20% 29% 19%	1980
November	1st to 10th	Day	27% 6% 8% 26% 25% 8%	1747
	11th to 20th	Day	33% 6% 12% 25% 21% 3	1710
	21st to end	Day	34% 4 12% 24% 20% 6%	1610
December	1st to 10th	Day	41% 7% 11% 19% 16% 6%	1520
	11th to 20th	Day	58% 6% 9% 13% 11% 3	1928
	21st to end	Day	48% 13% 15% 15% 8% 2	2794
January	1st to 10th	Night	38% 12% 15% 25% 8% 3	4377
	11th to 20th	Night	50% 7% 13% 14% 10% 6%	4110
	21st to end	Night	48% 9% 13% 15% 11% 4	4521
February	1st to 10th	Night	36% 4 9% 22% 21% 8%	2397
	11th to 20th	Night	28% 5% 12% 23% 25% 7%	2149
	21st to end	Night	31% 5% 10% 26% 22% 6%	1776
March	1st to 10th	Night	40% 6% 11% 18% 18% 6%	2080
	11th to 20th	Night	35% 6% 7% 24% 21% 8%	1980
	21st to end	Night	32% 6% 11% 24% 19% 8%	2104
April	1st to 10th	Night	30% 5% 14% 22% 21% 8%	1800
	11th to 20th	Night	23% 5% 12% 27% 21% 12%	1779
	21st to end	Night	16% 5% 14% 28% 30% 7%	1800
May	1st to 10th	Night	15% 4 10% 23% 33% 15%	1787
	11th to 20th	Night	12% 2 9% 31% 31% 14%	1452
	21st to end	Night	10% 5% 12% 35% 28% 10%	1552
June	1st to 10th	Night	13% 3 10% 25% 33% 16%	1440
	11th to 20th	Night	5% 2 7% 20% 33% 33%	1440
	21st to end	Night	7% 2 1 14% 31% 45%	1440
July	1st to 10th	Night	4 1 2 8% 24% 62%	1400
	11th to 20th	Night	5% 1 3 10% 23% 57%	1443
	21st to end	Night	8% 2 3 6% 26% 55%	1674
August	1st to 10th	Night	7% 1 3 13% 29% 47%	1602
	11th to 20th	Night	7% 1 2 10% 29% 51%	1756
	21st to end	Night	5% 1 2 10% 33% 50%	1980
September	1st to 10th	Night	4 1 3 8% 29% 55%	1800
	11th to 20th	Night	7% 3 4 20% 38% 28%	1800
	21st to end	Night	7% 2 4 19% 36% 32%	2015
October	1st to 10th	Night	14% 3 6% 17% 29% 31%	2160
	11th to 20th	Night	13% 4 8% 19% 28% 29%	2160
	21st to end	Night	14% 3 7% 22% 31% 24%	2376
November	1st to 10th	Night	22% 5% 9% 25% 24% 15%	2330
	11th to 20th	Night	25% 5% 10% 25% 27% 8%	2470
	21st to end	Night	26% 4 9% 24% 27% 9%	2569
December	1st to 10th	Night	34% 6% 11% 21% 18% 9%	2660
	11th to 20th	Night	49% 7% 10% 16% 14% 4	3276
	21st to end	Night	46% 12% 13% 17% 9% 3	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	30% 6% 18% 22% 17% 6%	194
	11th to 20th	Day	18% 6% 16% 25% 20% 15%	370
	21st to end	Day	16% 5% 17% 25% 21% 16%	407
February	1st to 10th	Day	17% 8% 17% 19% 21% 18%	353
	11th to 20th	Day	14% 8% 24% 24% 19% 12%	392
	21st to end	Day	14% 10% 23% 23% 23% 8%	346
March	1st to 10th	Day	16% 8% 19% 28% 21% 7%	420
	11th to 20th	Day	17% 8% 18% 26% 17% 13%	420
	21st to end	Day	14% 9% 24% 26% 19% 8%	462
April	1st to 10th	Day	15% 10% 22% 27% 18% 9%	420
	11th to 20th	Day	9% 7% 26% 29% 18% 11%	412
	21st to end	Day	6% 8% 23% 30% 21% 12%	420
May	1st to 10th	Day	5% 7% 26% 30% 22% 10%	423
	11th to 20th	Day	4 6% 26% 28% 25% 11%	448
	21st to end	Day	4 5% 19% 26% 31% 15%	485
June	1st to 10th	Day	4 6% 20% 31% 27% 13%	450
	11th to 20th	Day	1 6% 19% 37% 31% 7%	450
	21st to end	Day	1 2 15% 32% 36% 13%	450
July	1st to 10th	Day	1 1 12% 34% 43% 9%	446
	11th to 20th	Day	1 1 7% 33% 45% 14%	444
	21st to end	Day	1 6% 35% 41% 17%	487
August	1st to 10th	Day	2 2 10% 34% 40% 12%	447
	11th to 20th	Day	1 1 11% 36% 35% 16%	437
	21st to end	Day	1 1 7% 34% 43% 15%	495
September	1st to 10th	Day	1 2 8% 32% 43% 14%	450
	11th to 20th	Day	2 2 16% 30% 32% 17%	450
	21st to end	Day	3 2 12% 30% 35% 19%	450
October	1st to 10th	Day	1 4 18% 25% 28% 24%	450
	11th to 20th	Day	5% 4 11% 21% 31% 28%	450
	21st to end	Day	7% 4 13% 23% 30% 23%	495
November	1st to 10th	Day	6% 6% 17% 20% 27% 24%	343
	11th to 20th	Day	8% 3 15% 21% 34% 18%	270
	21st to end	Day	9% 1 13% 31% 33% 13%	222
December	1st to 10th	Day	17% 6% 14% 23% 24% 16%	180
	11th to 20th	Day	17% 3 20% 22% 23% 14%	180
	21st to end	Day	18% 8% 18% 26% 23% 7%	198
January	1st to 10th	Night	18% 4 15% 34% 24% 5%	760
	11th to 20th	Night	16% 4 12% 37% 27% 5%	760
	21st to end	Night	14% 4 15% 36% 27% 5%	836
February	1st to 10th	Night	18% 3 14% 35% 28% 3	738
	11th to 20th	Night	13% 5% 18% 34% 26% 5%	704
	21st to end	Night	14% 5% 20% 41% 18% 3	592
March	1st to 10th	Night	17% 6% 17% 34% 23% 3	720
	11th to 20th	Night	14% 5% 18% 36% 24% 3	720
	21st to end	Night	13% 6% 21% 38% 20% 1	792
April	1st to 10th	Night	12% 4 21% 40% 21% 1	720
	11th to 20th	Night	7% 7% 26% 36% 20% 4	711
	21st to end	Night	4 4 25% 38% 25% 3	720
May	1st to 10th	Night	3 3 24% 44% 22% 4	707
	11th to 20th	Night	4 2 19% 45% 29% 2	390
	21st to end	Night	3 3 24% 41% 29% 1	389
June	1st to 10th	Night	4 1 22% 46% 25% 1	360
	11th to 20th	Night	1 2 20% 52% 25% 1	360
	21st to end	Night	1 15% 52% 31% 2	360
July	1st to 10th	Night	1 6% 55% 37% 1	350
	11th to 20th	Night	1 1 4 54% 39% 2	399
	21st to end	Night	1 1 5% 45% 45% 3	591
August	1st to 10th	Night	2 1 7% 44% 44% 3	537
	11th to 20th	Night	1 1 11% 47% 37% 3	688
	21st to end	Night	1 6% 47% 43% 2	792
September	1st to 10th	Night	1 8% 48% 40% 3	720
	11th to 20th	Night	2 2 12% 44% 35% 5%	720
	21st to end	Night	2 1 13% 40% 37% 7%	720
October	1st to 10th	Night	4 3 13% 39% 32% 8%	720
	11th to 20th	Night	4 3 12% 35% 40% 6%	720
	21st to end	Night	5% 3 10% 35% 35% 11%	792
November	1st to 10th	Night	8% 3 11% 37% 34% 7%	740
	11th to 20th	Night	9% 1 11% 43% 31% 5%	760
	21st to end	Night	10% 2 13% 38% 32% 5%	760
December	1st to 10th	Night	14% 4 13% 37% 26% 6%	760
	11th to 20th	Night	20% 4 14% 35% 24% 4	760
	21st to end	Night	17% 7% 18% 35% 21% 2	836

Page generated at 2024-02-02 02:20:29. Version ac07

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