Gogama
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gogama 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	17% 12% 5% 9% 7% 4 5% 4 5% 6% 27%	77758
	Night	16% 14% 5% 9% 8% 4 5% 4 4 5% 24%	81130
Transparency	Day	58% 7% 11% 16% 8% 1	77450
	Night	61% 6% 10% 15% 7% 1	80973
Seeing	Day	22% 15% 32% 21% 8% 2	14266
	Night	23% 13% 31% 24% 8% 1	23623

By Month

Percentage Cloud Cover NE (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	12% 20% 10% 13% 7% 5% 7% 4 5% 5% 11%	2208
	11th to 20th	Day	9% 13% 6% 14% 13% 4 7% 5% 5% 5% 18%	2340
	21st to end	Day	12% 20% 12% 14% 8% 4 4 4 5% 5% 12%	2821
February	1st to 10th	Day	8% 13% 6% 10% 11% 6% 8% 5% 5% 6% 21%	1656
	11th to 20th	Day	11% 17% 6% 10% 7% 5% 6% 5% 5% 7% 21%	1573
	21st to end	Day	10% 17% 8% 10% 9% 4 5% 4 4 5% 23%	1418
March	1st to 10th	Day	13% 13% 5% 10% 8% 5% 6% 5% 4 5% 27%	1869
	11th to 20th	Day	12% 14% 4 9% 8% 3 4 4 4 6% 31%	1980
	21st to end	Day	16% 14% 5% 8% 6% 3 3 3 4 5% 33%	2178
April	1st to 10th	Day	20% 14% 6% 10% 7% 3 4 5% 4 5% 23%	2155
	11th to 20th	Day	20% 11% 4 7% 6% 3 3 4 5% 5% 31%	2312
	21st to end	Day	20% 10% 4 7% 5% 2 4 4 4 6% 33%	2340
May	1st to 10th	Day	16% 11% 4 8% 7% 4 5% 5% 5% 7% 29%	2353
	11th to 20th	Day	20% 8% 3 6% 5% 3 4 5% 5% 6% 34%	2478
	21st to end	Day	17% 7% 2 6% 6% 3 6% 6% 5% 8% 34%	2910
June	1st to 10th	Day	20% 9% 3 6% 6% 4 5% 4 5% 7% 32%	2700
	11th to 20th	Day	16% 8% 3 6% 6% 3 4 4 6% 7% 36%	2700
	21st to end	Day	18% 7% 3 7% 6% 4 5% 5% 6% 8% 32%	2700
July	1st to 10th	Day	16% 6% 2 5% 5% 4 5% 5% 6% 7% 38%	2700
	11th to 20th	Day	15% 6% 3 6% 6% 3 5% 5% 6% 9% 36%	2700
	21st to end	Day	15% 7% 3 6% 7% 4 5% 5% 7% 9% 32%	2821
August	1st to 10th	Day	14% 7% 4 7% 7% 3 6% 6% 6% 8% 32%	2327
	11th to 20th	Day	17% 6% 3 6% 5% 4 6% 6% 6% 8% 35%	2303
	21st to end	Day	19% 6% 3 6% 6% 3 5% 5% 5% 8% 35%	2574
September	1st to 10th	Day	19% 8% 3 6% 5% 4 5% 6% 5% 7% 33%	2180
	11th to 20th	Day	21% 8% 3 6% 5% 3 4 4 6% 8% 33%	1980
	21st to end	Day	22% 11% 2 6% 6% 3 3 4 4 6% 32%	1980
October	1st to 10th	Day	23% 16% 3 6% 5% 3 3 3 4 6% 28%	1832
	11th to 20th	Day	26% 19% 5% 8% 6% 3 4 3 4 5% 19%	1800
	21st to end	Day	25% 24% 6% 7% 7% 3 3 3 4 5% 15%	1812
November	1st to 10th	Day	22% 17% 6% 10% 5% 3 4 3 4 6% 20%	1557
	11th to 20th	Day	20% 18% 7% 13% 8% 5% 5% 4 4 4 13%	1520
	21st to end	Day	21% 21% 8% 14% 8% 4 4 3 3 3 11%	1520
December	1st to 10th	Day	15% 19% 9% 13% 9% 4 5% 5% 4 6% 11%	1359
	11th to 20th	Day	15% 19% 6% 12% 10% 5% 5% 5% 4 5% 16%	1671
	21st to end	Day	18% 21% 11% 17% 9% 3 3 2 2 3 10%	2431
January	1st to 10th	Night	13% 19% 8% 13% 10% 6% 7% 4 5% 4 10%	4748
	11th to 20th	Night	10% 16% 6% 12% 11% 6% 7% 6% 5% 5% 17%	4628
	21st to end	Night	12% 20% 11% 13% 9% 5% 5% 4 4 4 13%	4843
February	1st to 10th	Night	10% 13% 5% 12% 12% 6% 7% 5% 5% 6% 20%	2399
	11th to 20th	Night	11% 15% 7% 10% 10% 5% 6% 4 4 5% 23%	2273
	21st to end	Night	12% 16% 8% 11% 8% 5% 6% 4 5% 5% 21%	1834
March	1st to 10th	Night	10% 13% 5% 12% 8% 5% 5% 4 4 6% 27%	2078
	11th to 20th	Night	16% 13% 6% 9% 8% 3 5% 3 3 6% 27%	1979
	21st to end	Night	13% 12% 4 7% 5% 4 5% 4 5% 6% 35%	2178
April	1st to 10th	Night	20% 13% 6% 8% 6% 3 4 4 5% 5% 26%	1819
	11th to 20th	Night	20% 11% 4 8% 5% 3 3 3 4 6% 33%	1597
	21st to end	Night	19% 12% 4 5% 6% 3 3 3 4 5% 35%	1620
May	1st to 10th	Night	14% 12% 3 6% 5% 3 5% 4 5% 8% 35%	1607
	11th to 20th	Night	19% 7% 3 7% 7% 4 5% 4 5% 8% 32%	1415
	21st to end	Night	17% 7% 3 6% 4 3 5% 3 5% 7% 41%	1362
June	1st to 10th	Night	18% 8% 3 5% 6% 4 5% 5% 4 8% 35%	1260
	11th to 20th	Night	17% 8% 2 5% 5% 3 4 4 7% 7% 37%	1260
	21st to end	Night	16% 6% 2 5% 6% 3 5% 5% 6% 8% 39%	1260
July	1st to 10th	Night	13% 5% 2 5% 4 4 4 5% 6% 9% 42%	1260
	11th to 20th	Night	13% 5% 2 5% 5% 3 5% 4 6% 9% 43%	1260
	21st to end	Night	13% 6% 3 4 6% 3 4 5% 6% 8% 42%	1492
August	1st to 10th	Night	12% 7% 3 6% 7% 4 5% 6% 6% 7% 38%	1611
	11th to 20th	Night	14% 7% 3 4 4 3 5% 4 6% 8% 42%	1598
	21st to end	Night	18% 7% 3 5% 5% 3 4 5% 5% 6% 39%	1782
September	1st to 10th	Night	18% 7% 2 5% 4 4 4 3 5% 6% 41%	1759
	11th to 20th	Night	19% 10% 3 6% 4 2 3 4 5% 5% 40%	1980
	21st to end	Night	20% 9% 3 5% 5% 4 4 4 5% 6% 35%	1980
October	1st to 10th	Night	21% 12% 3 6% 6% 3 4 4 4 6% 32%	2128
	11th to 20th	Night	28% 15% 5% 7% 6% 3 4 3 4 5% 22%	2160
	21st to end	Night	25% 21% 5% 7% 5% 3 4 4 3 4 18%	2542
November	1st to 10th	Night	19% 16% 5% 8% 6% 3 5% 4 5% 5% 23%	2520
	11th to 20th	Night	21% 15% 6% 11% 10% 4 4 3 4 4 16%	2660
	21st to end	Night	19% 19% 8% 13% 10% 4 5% 4 3 3 11%	2660
December	1st to 10th	Night	16% 19% 7% 14% 10% 5% 5% 4 5% 3 12%	2816
	11th to 20th	Night	17% 18% 7% 11% 10% 5% 5% 4 4 5% 15%	3526
	21st to end	Night	20% 21% 7% 15% 11% 3 4 3 3 3 10%	5236

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	73% 7% 10% 8% 2	2209
	11th to 20th	Day	66% 6% 9% 14% 4	2340
	21st to end	Day	75% 6% 6% 8% 5%	2821
February	1st to 10th	Day	64% 6% 8% 13% 8%	1656
	11th to 20th	Day	62% 5% 10% 13% 10% 1	1582
	21st to end	Day	65% 3 7% 15% 9% 1	1418
March	1st to 10th	Day	59% 6% 10% 13% 10% 1	1872
	11th to 20th	Day	56% 5% 9% 19% 10% 2	1980
	21st to end	Day	55% 4 8% 17% 13% 2	2178
April	1st to 10th	Day	64% 6% 8% 13% 8% 1	2155
	11th to 20th	Day	55% 5% 9% 21% 9% 2	2312
	21st to end	Day	53% 5% 10% 16% 14% 3	2340
May	1st to 10th	Day	54% 7% 12% 16% 10% 2	2353
	11th to 20th	Day	49% 7% 9% 20% 13% 2	2482
	21st to end	Day	47% 9% 13% 21% 9% 2	2910
June	1st to 10th	Day	51% 7% 11% 20% 10% 1	2700
	11th to 20th	Day	47% 7% 11% 21% 12% 1	2700
	21st to end	Day	50% 8% 13% 18% 11%	2700
July	1st to 10th	Day	42% 8% 15% 23% 11%	2626
	11th to 20th	Day	42% 9% 15% 25% 8%	2619
	21st to end	Day	47% 9% 14% 23% 6%	2664
August	1st to 10th	Day	48% 10% 16% 20% 6%	2314
	11th to 20th	Day	45% 10% 14% 23% 7% 1	2303
	21st to end	Day	47% 7% 16% 21% 8%	2574
September	1st to 10th	Day	50% 8% 15% 18% 9% 1	2180
	11th to 20th	Day	50% 8% 16% 21% 5%	1980
	21st to end	Day	54% 7% 13% 20% 6%	1980
October	1st to 10th	Day	59% 6% 12% 17% 6%	1832
	11th to 20th	Day	69% 5% 9% 12% 4	1800
	21st to end	Day	74% 5% 8% 8% 5%	1812
November	1st to 10th	Day	67% 7% 11% 10% 5%	1557
	11th to 20th	Day	76% 6% 7% 8% 3	1520
	21st to end	Day	81% 5% 8% 6% 1	1520
December	1st to 10th	Day	74% 7% 8% 7% 4	1359
	11th to 20th	Day	69% 7% 8% 13% 3	1671
	21st to end	Day	84% 3 3 8% 2	2431
January	1st to 10th	Night	76% 7% 7% 9% 2	4748
	11th to 20th	Night	68% 6% 8% 14% 4	4628
	21st to end	Night	75% 5% 7% 9% 4	4843
February	1st to 10th	Night	64% 5% 10% 12% 8% 1	2399
	11th to 20th	Night	64% 4 9% 15% 7%	2275
	21st to end	Night	64% 6% 8% 14% 7% 1	1834
March	1st to 10th	Night	58% 5% 10% 15% 11% 2	2088
	11th to 20th	Night	60% 4 9% 16% 9% 1	1980
	21st to end	Night	51% 6% 10% 16% 15% 3	2178
April	1st to 10th	Night	58% 5% 9% 15% 11% 1	1819
	11th to 20th	Night	53% 5% 8% 19% 13% 2	1597
	21st to end	Night	51% 4 11% 16% 15% 3	1620
May	1st to 10th	Night	48% 7% 10% 21% 12% 1	1607
	11th to 20th	Night	50% 6% 9% 21% 12% 2	1416
	21st to end	Night	44% 6% 14% 22% 12% 2	1363
June	1st to 10th	Night	48% 7% 12% 19% 11% 2	1260
	11th to 20th	Night	43% 8% 10% 21% 17% 1	1260
	21st to end	Night	43% 8% 14% 22% 12% 1	1260
July	1st to 10th	Night	37% 9% 15% 26% 13%	1225
	11th to 20th	Night	37% 9% 15% 29% 10%	1218
	21st to end	Night	40% 9% 18% 27% 6%	1409
August	1st to 10th	Night	44% 10% 16% 21% 8% 1	1600
	11th to 20th	Night	39% 8% 21% 25% 8%	1598
	21st to end	Night	44% 9% 15% 23% 8% 1	1782
September	1st to 10th	Night	44% 7% 16% 22% 10% 1	1759
	11th to 20th	Night	47% 7% 17% 23% 6%	1980
	21st to end	Night	49% 8% 16% 21% 6%	1980
October	1st to 10th	Night	54% 7% 11% 20% 7%	2128
	11th to 20th	Night	65% 7% 10% 13% 4	2160
	21st to end	Night	70% 5% 10% 11% 4	2542
November	1st to 10th	Night	62% 8% 13% 14% 4	2520
	11th to 20th	Night	72% 6% 10% 9% 4	2660
	21st to end	Night	79% 6% 8% 5% 2	2660
December	1st to 10th	Night	77% 6% 7% 8% 3	2816
	11th to 20th	Night	71% 6% 9% 10% 3	3525
	21st to end	Night	80% 4 6% 6% 3	5236

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	22% 18% 35% 17% 6% 2	180
	11th to 20th	Day	18% 14% 37% 26% 4 2	218
	21st to end	Day	22% 12% 34% 26% 5%	297
February	1st to 10th	Day	22% 23% 37% 14% 3 1	252
	11th to 20th	Day	23% 23% 37% 13% 3 2	240
	21st to end	Day	19% 35% 37% 8% 1	198
March	1st to 10th	Day	21% 23% 36% 17% 3	312
	11th to 20th	Day	22% 22% 31% 17% 6% 1	420
	21st to end	Day	27% 16% 32% 18% 6%	462
April	1st to 10th	Day	26% 15% 33% 20% 6%	420
	11th to 20th	Day	28% 17% 27% 18% 6% 4	412
	21st to end	Day	29% 16% 26% 18% 9% 3	420
May	1st to 10th	Day	22% 16% 34% 18% 8% 2	423
	11th to 20th	Day	20% 15% 36% 17% 8% 4	447
	21st to end	Day	20% 17% 31% 23% 8%	670
June	1st to 10th	Day	22% 13% 36% 21% 7% 2	630
	11th to 20th	Day	21% 15% 32% 23% 7% 1	630
	21st to end	Day	19% 12% 29% 24% 13% 2	630
July	1st to 10th	Day	14% 12% 36% 25% 12% 1	621
	11th to 20th	Day	16% 10% 32% 28% 12% 2	618
	21st to end	Day	16% 10% 31% 29% 10% 4	676
August	1st to 10th	Day	15% 11% 27% 28% 14% 5%	446
	11th to 20th	Day	16% 7% 26% 27% 15% 9%	439
	21st to end	Day	21% 11% 31% 19% 13% 6%	495
September	1st to 10th	Day	22% 10% 30% 24% 11% 4	450
	11th to 20th	Day	24% 13% 29% 23% 8% 3	450
	21st to end	Day	28% 14% 26% 20% 10% 2	450
October	1st to 10th	Day	29% 16% 27% 18% 8% 2	450
	11th to 20th	Day	32% 18% 31% 15% 2 1	450
	21st to end	Day	33% 20% 32% 13% 1 1	327
November	1st to 10th	Day	30% 20% 35% 13% 1	215
	11th to 20th	Day	27% 27% 31% 12% 3	180
	21st to end	Day	33% 21% 37% 8% 1 1	180
December	1st to 10th	Day	18% 22% 37% 17% 6% 1	180
	11th to 20th	Day	29% 17% 40% 9% 4 1	180
	21st to end	Day	30% 19% 32% 14% 5% 1	198
January	1st to 10th	Night	23% 13% 40% 19% 5% 1	950
	11th to 20th	Night	25% 13% 33% 22% 7%	950
	21st to end	Night	20% 12% 28% 29% 10% 1	1017
February	1st to 10th	Night	17% 16% 37% 24% 6%	739
	11th to 20th	Night	20% 15% 35% 21% 8% 1	703
	21st to end	Night	21% 16% 37% 21% 5%	592
March	1st to 10th	Night	18% 19% 33% 25% 4	720
	11th to 20th	Night	24% 17% 34% 19% 6% 1	720
	21st to end	Night	19% 13% 38% 23% 6% 1	792
April	1st to 10th	Night	25% 17% 28% 24% 5%	650
	11th to 20th	Night	25% 13% 26% 27% 8% 1	533
	21st to end	Night	24% 11% 30% 24% 11%	540
May	1st to 10th	Night	19% 8% 34% 30% 9%	527
	11th to 20th	Night	21% 12% 29% 29% 7% 2	354
	21st to end	Night	19% 12% 32% 30% 6% 1	389
June	1st to 10th	Night	21% 8% 31% 33% 7%	360
	11th to 20th	Night	20% 9% 30% 29% 10% 1	360
	21st to end	Night	18% 6% 28% 36% 11%	360
July	1st to 10th	Night	15% 5% 36% 32% 11%	350
	11th to 20th	Night	15% 8% 30% 33% 14%	348
	21st to end	Night	18% 4 25% 37% 15% 1	502
August	1st to 10th	Night	16% 3 28% 34% 17% 1	537
	11th to 20th	Night	16% 6% 23% 31% 22% 1	534
	21st to end	Night	21% 7% 30% 24% 15% 2	594
September	1st to 10th	Night	21% 8% 28% 26% 15% 2	659
	11th to 20th	Night	24% 10% 28% 23% 13% 2	720
	21st to end	Night	25% 9% 27% 27% 12% 2	720
October	1st to 10th	Night	28% 10% 30% 24% 8% 1	720
	11th to 20th	Night	35% 15% 28% 17% 5% 1	720
	21st to end	Night	35% 14% 27% 20% 4 1	792
November	1st to 10th	Night	26% 15% 37% 17% 4 1	740
	11th to 20th	Night	31% 15% 30% 18% 5%	760
	21st to end	Night	28% 16% 36% 16% 3 1	760
December	1st to 10th	Night	26% 17% 32% 20% 5% 1	916
	11th to 20th	Night	26% 17% 32% 18% 6% 1	950
	21st to end	Night	28% 16% 30% 19% 6% 2	1045

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