Gilbert-Baker Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gilbert-Baker Campground clear sky chart from 2005-11-06 to 2024-02-25.

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	7% 6% 2 4 4 3 4 4 6% 8% 52%	78389
	Night	6% 6% 3 5% 5% 3 4 4 5% 8% 52%	80978
Transparency	Day	29% 6% 14% 27% 18% 5%	78093
	Night	30% 7% 15% 27% 17% 5%	80796
Seeing	Day	11% 12% 32% 28% 15% 3	14781
	Night	9% 12% 38% 32% 9% 1	24963

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	2 6% 3 7% 6% 4 4 5% 6% 7% 50%	2538
	11th to 20th	Day	4 7% 4 6% 5% 5% 6% 7% 8% 9% 41%	2540
	21st to end	Day	3 5% 3 5% 3 2 3 3 5% 7% 61%	2898
February	1st to 10th	Day	5% 10% 6% 7% 5% 4 6% 5% 5% 6% 42%	1710
	11th to 20th	Day	4 8% 5% 7% 5% 3 5% 5% 6% 7% 46%	1815
	21st to end	Day	4 9% 4 6% 5% 2 4 4 5% 7% 49%	1520
March	1st to 10th	Day	5% 9% 2 5% 4 3 4 4 5% 8% 51%	1800
	11th to 20th	Day	6% 8% 2 5% 4 3 3 4 5% 9% 51%	1864
	21st to end	Day	9% 10% 3 6% 5% 3 4 4 6% 8% 44%	2365
April	1st to 10th	Day	9% 7% 3 5% 4 3 5% 5% 6% 9% 45%	2160
	11th to 20th	Day	12% 8% 3 6% 5% 3 4 5% 6% 7% 41%	2131
	21st to end	Day	13% 8% 3 4 4 2 5% 5% 5% 7% 44%	2236
May	1st to 10th	Day	13% 6% 3 5% 5% 3 4 5% 5% 8% 43%	2376
	11th to 20th	Day	16% 8% 1 4 4 3 5% 5% 6% 8% 38%	2478
	21st to end	Day	12% 7% 3 5% 5% 3 4 6% 6% 9% 40%	2724
June	1st to 10th	Day	6% 3 2 4 4 3 5% 6% 6% 10% 53%	2520
	11th to 20th	Day	8% 4 1 3 4 2 5% 4 7% 9% 53%	2520
	21st to end	Day	5% 3 1 2 3 2 4 4 6% 9% 60%	2520
July	1st to 10th	Day	5% 2 2 4 3 3 4 6% 7% 9% 54%	2520
	11th to 20th	Day	5% 2 1 3 3 3 4 4 7% 9% 59%	2520
	21st to end	Day	5% 3 1 3 4 3 4 5% 7% 9% 55%	2742
August	1st to 10th	Day	4 3 1 4 5% 3 5% 6% 7% 9% 54%	2495
	11th to 20th	Day	5% 3 1 3 3 2 3 5% 5% 8% 62%	2145
	21st to end	Day	5% 3 1 3 4 2 3 4 6% 8% 62%	2376
September	1st to 10th	Day	7% 4 1 4 4 2 3 3 4 6% 62%	2160
	11th to 20th	Day	7% 3 1 3 2 1 3 3 3 8% 65%	2100
	21st to end	Day	8% 4 2 3 3 2 2 3 4 7% 64%	1980
October	1st to 10th	Day	11% 5% 2 3 3 3 4 4 4 6% 55%	1869
	11th to 20th	Day	8% 5% 1 4 4 2 4 3 4 6% 60%	1800
	21st to end	Day	6% 6% 2 4 4 2 3 4 5% 7% 57%	1795
November	1st to 10th	Day	5% 5% 2 4 4 2 4 4 8% 8% 54%	1673
	11th to 20th	Day	4 5% 3 6% 4 2 4 4 4 8% 56%	1710
	21st to end	Day	5% 7% 4 3 3 2 3 4 5% 8% 56%	1549
December	1st to 10th	Day	4 6% 3 6% 6% 3 4 4 5% 8% 51%	1520
	11th to 20th	Day	3 5% 2 4 4 2 4 4 6% 10% 55%	1926
	21st to end	Day	3 9% 4 7% 6% 3 4 3 3 6% 50%	2794
January	1st to 10th	Night	2 7% 3 7% 6% 3 4 4 6% 8% 51%	4417
	11th to 20th	Night	2 6% 3 7% 5% 3 4 4 6% 9% 51%	4430
	21st to end	Night	2 4 3 5% 4 3 4 5% 5% 7% 58%	4800
February	1st to 10th	Night	4 10% 4 9% 6% 3 5% 7% 6% 7% 41%	2470
	11th to 20th	Night	4 10% 4 6% 7% 3 5% 6% 6% 8% 42%	2251
	21st to end	Night	4 8% 3 7% 5% 3 5% 5% 5% 6% 49%	1830
March	1st to 10th	Night	6% 7% 4 7% 5% 3 4 4 4 6% 51%	2160
	11th to 20th	Night	7% 7% 3 5% 4 3 4 5% 6% 9% 47%	2093
	21st to end	Night	10% 7% 3 5% 6% 3 5% 5% 5% 8% 43%	1990
April	1st to 10th	Night	11% 7% 3 5% 3 3 4 4 4 7% 48%	1800
	11th to 20th	Night	12% 8% 2 5% 5% 3 6% 4 5% 7% 43%	1777
	21st to end	Night	14% 7% 3 5% 6% 3 4 4 6% 7% 42%	1723
May	1st to 10th	Night	13% 6% 3 3 5% 3 5% 6% 5% 7% 45%	1581
	11th to 20th	Night	15% 7% 2 4 4 3 4 4 6% 8% 43%	1417
	21st to end	Night	14% 5% 2 4 4 3 4 4 6% 9% 46%	1552
June	1st to 10th	Night	7% 4 2 4 4 4 4 7% 6% 11% 49%	1440
	11th to 20th	Night	9% 3 1 3 3 3 4 5% 7% 10% 52%	1440
	21st to end	Night	5% 4 1 3 3 2 5% 4 7% 9% 58%	1440
July	1st to 10th	Night	7% 3 2 4 4 3 4 4 6% 10% 54%	1440
	11th to 20th	Night	4 3 1 3 3 2 3 4 6% 11% 59%	1440
	21st to end	Night	3 2 1 4 4 2 5% 6% 7% 7% 57%	1576
August	1st to 10th	Night	4 3 2 5% 5% 3 4 6% 6% 10% 51%	1441
	11th to 20th	Night	3 3 2 3 4 2 4 4 5% 8% 62%	1756
	21st to end	Night	3 4 2 4 4 3 4 5% 6% 8% 59%	1980
September	1st to 10th	Night	7% 5% 2 3 4 2 3 4 3 7% 60%	1800
	11th to 20th	Night	6% 4 2 3 3 3 3 3 5% 6% 61%	1859
	21st to end	Night	10% 4 2 3 3 2 3 3 4 5% 62%	1980
October	1st to 10th	Night	12% 5% 3 4 3 2 4 4 4 6% 53%	2088
	11th to 20th	Night	9% 6% 2 4 4 3 4 3 5% 6% 56%	2160
	21st to end	Night	8% 5% 2 4 4 2 3 3 5% 7% 55%	2542
November	1st to 10th	Night	7% 5% 2 4 4 3 4 4 5% 9% 54%	2405
	11th to 20th	Night	4 5% 2 5% 6% 3 4 5% 6% 7% 52%	2470
	21st to end	Night	4 6% 3 5% 3 2 4 4 6% 8% 54%	2626
December	1st to 10th	Night	4 6% 3 6% 5% 4 4 4 5% 8% 52%	2660
	11th to 20th	Night	3 6% 3 4 4 2 4 4 6% 8% 56%	3271
	21st to end	Night	4 10% 4 7% 5% 2 4 4 4 7% 49%	4873

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	29% 6% 17% 29% 18% 1	2539
	11th to 20th	Day	35% 8% 17% 24% 13% 2	2540
	21st to end	Day	24% 5% 20% 33% 14% 5%	2898
February	1st to 10th	Day	41% 7% 15% 21% 13% 2	1710
	11th to 20th	Day	37% 8% 15% 22% 14% 5%	1825
	21st to end	Day	33% 5% 17% 23% 16% 5%	1520
March	1st to 10th	Day	32% 5% 14% 28% 18% 3	1800
	11th to 20th	Day	31% 5% 15% 27% 19% 3	1864
	21st to end	Day	39% 7% 15% 27% 11% 1	2365
April	1st to 10th	Day	34% 9% 17% 24% 12% 4	2160
	11th to 20th	Day	40% 7% 14% 20% 16% 3	2134
	21st to end	Day	39% 6% 14% 28% 13% 1	2236
May	1st to 10th	Day	38% 7% 16% 28% 10% 1	2376
	11th to 20th	Day	41% 8% 18% 23% 9% 1	2482
	21st to end	Day	38% 9% 17% 23% 11% 1	2724
June	1st to 10th	Day	25% 8% 19% 29% 14% 4	2520
	11th to 20th	Day	27% 6% 16% 25% 19% 7%	2520
	21st to end	Day	20% 6% 11% 29% 25% 8%	2520
July	1st to 10th	Day	24% 8% 13% 24% 24% 7%	2451
	11th to 20th	Day	19% 6% 13% 24% 23% 15%	2445
	21st to end	Day	23% 6% 13% 25% 21% 11%	2590
August	1st to 10th	Day	23% 7% 15% 28% 18% 8%	2479
	11th to 20th	Day	20% 6% 14% 27% 22% 11%	2145
	21st to end	Day	20% 5% 10% 23% 29% 14%	2376
September	1st to 10th	Day	24% 4 8% 21% 27% 15%	2160
	11th to 20th	Day	20% 4 9% 26% 28% 13%	2100
	21st to end	Day	22% 4 9% 31% 29% 5%	1980
October	1st to 10th	Day	30% 6% 10% 25% 25% 5%	1869
	11th to 20th	Day	26% 6% 11% 29% 21% 7%	1800
	21st to end	Day	26% 5% 15% 32% 17% 6%	1795
November	1st to 10th	Day	25% 7% 16% 26% 19% 7%	1673
	11th to 20th	Day	26% 5% 14% 30% 21% 4	1710
	21st to end	Day	27% 5% 14% 29% 21% 4	1549
December	1st to 10th	Day	31% 6% 19% 24% 18% 3	1520
	11th to 20th	Day	24% 7% 15% 36% 16% 1	1924
	21st to end	Day	35% 7% 10% 30% 16% 2	2794
January	1st to 10th	Night	30% 7% 12% 35% 15% 2	4417
	11th to 20th	Night	29% 7% 22% 23% 16% 3	4430
	21st to end	Night	24% 7% 21% 33% 14% 2	4800
February	1st to 10th	Night	39% 7% 17% 22% 12% 2	2470
	11th to 20th	Night	39% 8% 15% 22% 12% 5%	2251
	21st to end	Night	33% 7% 14% 26% 16% 5%	1830
March	1st to 10th	Night	33% 5% 13% 26% 19% 3	2160
	11th to 20th	Night	32% 7% 13% 26% 18% 3	2093
	21st to end	Night	38% 6% 17% 24% 14% 2	1990
April	1st to 10th	Night	36% 7% 14% 23% 17% 4	1800
	11th to 20th	Night	39% 6% 13% 24% 14% 3	1777
	21st to end	Night	41% 7% 12% 25% 14% 1	1723
May	1st to 10th	Night	37% 8% 14% 26% 14% 1	1581
	11th to 20th	Night	38% 10% 17% 25% 9% 1	1418
	21st to end	Night	35% 10% 19% 22% 13% 2	1552
June	1st to 10th	Night	28% 11% 23% 24% 11% 3	1440
	11th to 20th	Night	26% 9% 18% 27% 14% 6%	1440
	21st to end	Night	21% 8% 15% 30% 21% 6%	1440
July	1st to 10th	Night	26% 7% 13% 30% 19% 5%	1400
	11th to 20th	Night	18% 7% 13% 26% 22% 14%	1392
	21st to end	Night	22% 8% 16% 27% 19% 8%	1488
August	1st to 10th	Night	25% 8% 17% 28% 17% 5%	1433
	11th to 20th	Night	21% 6% 14% 24% 26% 9%	1756
	21st to end	Night	22% 5% 11% 23% 26% 12%	1980
September	1st to 10th	Night	25% 4 8% 24% 28% 11%	1800
	11th to 20th	Night	24% 5% 10% 27% 24% 11%	1859
	21st to end	Night	26% 5% 8% 28% 24% 9%	1980
October	1st to 10th	Night	31% 6% 13% 21% 24% 5%	2088
	11th to 20th	Night	30% 4 10% 26% 21% 9%	2160
	21st to end	Night	28% 6% 13% 27% 19% 7%	2542
November	1st to 10th	Night	27% 5% 15% 27% 21% 6%	2405
	11th to 20th	Night	28% 6% 13% 28% 20% 5%	2470
	21st to end	Night	27% 5% 13% 28% 21% 5%	2626
December	1st to 10th	Night	30% 7% 14% 27% 19% 4	2660
	11th to 20th	Night	25% 6% 18% 35% 14% 2	3272
	21st to end	Night	34% 7% 12% 32% 12% 3	4873

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	8% 19% 33% 26% 12% 2	270
	11th to 20th	Day	13% 20% 37% 22% 7% 1	270
	21st to end	Day	10% 21% 48% 15% 4 2	297
February	1st to 10th	Day	11% 23% 46% 16% 3	270
	11th to 20th	Day	8% 26% 44% 18% 4	270
	21st to end	Day	9% 23% 43% 21% 3	210
March	1st to 10th	Day	8% 20% 39% 28% 5% 1	240
	11th to 20th	Day	12% 17% 41% 22% 6% 2	304
	21st to end	Day	16% 18% 36% 21% 7% 1	462
April	1st to 10th	Day	16% 19% 36% 23% 6%	420
	11th to 20th	Day	16% 25% 37% 16% 6%	412
	21st to end	Day	21% 12% 33% 22% 10% 2	496
May	1st to 10th	Day	16% 12% 32% 24% 14% 2	603
	11th to 20th	Day	21% 9% 23% 28% 17% 3	625
	21st to end	Day	16% 11% 29% 27% 14% 3	679
June	1st to 10th	Day	6% 6% 26% 32% 23% 7%	630
	11th to 20th	Day	10% 11% 34% 30% 12% 3	630
	21st to end	Day	9% 5% 29% 33% 21% 3	630
July	1st to 10th	Day	6% 3 24% 39% 23% 5%	621
	11th to 20th	Day	7% 4 26% 42% 18% 3	618
	21st to end	Day	7% 2 22% 40% 26% 3	684
August	1st to 10th	Day	4 3 27% 38% 25% 4	614
	11th to 20th	Day	5% 3 25% 34% 26% 6%	437
	21st to end	Day	5% 6% 23% 34% 25% 7%	495
September	1st to 10th	Day	8% 8% 24% 35% 20% 5%	450
	11th to 20th	Day	7% 8% 21% 34% 24% 6%	390
	21st to end	Day	9% 9% 32% 28% 14% 8%	270
October	1st to 10th	Day	13% 9% 25% 28% 17% 8%	270
	11th to 20th	Day	11% 15% 40% 17% 13% 4	270
	21st to end	Day	12% 15% 39% 22% 10% 2	297
November	1st to 10th	Day	6% 16% 41% 23% 10% 3	270
	11th to 20th	Day	10% 20% 39% 21% 9%	270
	21st to end	Day	11% 12% 45% 23% 6% 3	270
December	1st to 10th	Day	10% 18% 45% 21% 5%	270
	11th to 20th	Day	11% 18% 52% 13% 6%	270
	21st to end	Day	11% 24% 38% 21% 6%	297
January	1st to 10th	Night	6% 19% 38% 26% 8% 1	950
	11th to 20th	Night	9% 22% 40% 23% 6% 1	950
	21st to end	Night	7% 18% 43% 27% 5%	998
February	1st to 10th	Night	8% 18% 46% 23% 4	760
	11th to 20th	Night	9% 16% 43% 27% 5%	744
	21st to end	Night	8% 16% 47% 24% 5%	610
March	1st to 10th	Night	9% 15% 42% 28% 5% 1	720
	11th to 20th	Night	11% 9% 42% 31% 7% 1	720
	21st to end	Night	14% 13% 36% 33% 4 1	604
April	1st to 10th	Night	15% 13% 38% 29% 4	540
	11th to 20th	Night	16% 15% 39% 26% 3	533
	21st to end	Night	17% 13% 26% 33% 10%	540
May	1st to 10th	Night	16% 9% 30% 31% 11% 1	540
	11th to 20th	Night	18% 5% 28% 36% 12% 1	531
	21st to end	Night	15% 9% 33% 34% 7% 1	584
June	1st to 10th	Night	9% 5% 36% 35% 13% 2	540
	11th to 20th	Night	10% 6% 41% 37% 6%	540
	21st to end	Night	6% 4 35% 45% 10% 1	540
July	1st to 10th	Night	6% 3 29% 43% 18% 1	525
	11th to 20th	Night	4 4 31% 47% 14%	522
	21st to end	Night	4 2 27% 48% 18% 1	591
August	1st to 10th	Night	5% 3 28% 47% 15% 1	537
	11th to 20th	Night	4 2 30% 48% 16% 1	534
	21st to end	Night	3 3 27% 49% 16%	594
September	1st to 10th	Night	8% 5% 26% 44% 15% 1	540
	11th to 20th	Night	7% 7% 32% 37% 15% 2	540
	21st to end	Night	12% 6% 31% 36% 13%	540
October	1st to 10th	Night	15% 10% 32% 28% 14% 1	648
	11th to 20th	Night	11% 11% 34% 34% 10% 1	720
	21st to end	Night	10% 12% 41% 28% 9% 1	958
November	1st to 10th	Night	9% 8% 43% 30% 9% 1	925
	11th to 20th	Night	6% 17% 43% 27% 5% 1	950
	21st to end	Night	8% 16% 41% 29% 6%	950
December	1st to 10th	Night	8% 18% 47% 23% 5%	950
	11th to 20th	Night	8% 14% 44% 29% 5%	950
	21st to end	Night	11% 19% 43% 22% 5%	1045

Page generated at 2024-02-22 04:05:45. Version ac07

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