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 2025-02-25.

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	16% 13% 4 10% 6% 5% 4 3 5% 6% 28%	108235
	Night	15% 15% 5% 11% 6% 5% 4 3 4 5% 25%	110567
Transparency	Day	56% 6% 11% 18% 8% 1	111731
	Night	60% 6% 10% 16% 7% 1	115234
Seeing	Day	22% 15% 32% 21% 8% 2	15651
	Night	23% 13% 32% 24% 8% 1	24999

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	10% 18% 9% 21% 8% 8% 6% 3 4 4 10%	3158
	11th to 20th	Day	8% 16% 8% 16% 9% 7% 5% 3 4 5% 18%	3331
	21st to end	Day	8% 18% 10% 17% 7% 7% 6% 3 5% 5% 14%	4046
February	1st to 10th	Day	8% 15% 6% 12% 11% 8% 7% 3 5% 6% 20%	1800
	11th to 20th	Day	10% 19% 6% 12% 7% 6% 5% 5% 5% 7% 21%	1753
	21st to end	Day	10% 19% 6% 12% 8% 5% 5% 3 4 5% 23%	1541
March	1st to 10th	Day	14% 16% 4 9% 5% 5% 5% 4 5% 6% 27%	3245
	11th to 20th	Day	9% 18% 5% 15% 8% 4 4 3 4 5% 25%	3480
	21st to end	Day	14% 16% 6% 11% 6% 4 4 3 4 6% 27%	3815
April	1st to 10th	Day	19% 16% 4 11% 6% 4 4 3 4 5% 24%	2276
	11th to 20th	Day	20% 12% 4 8% 5% 4 4 3 5% 5% 30%	2442
	21st to end	Day	20% 11% 4 7% 4 3 4 3 4 6% 33%	2470
May	1st to 10th	Day	17% 10% 3 7% 5% 4 4 3 5% 7% 35%	4135
	11th to 20th	Day	15% 8% 3 8% 5% 5% 5% 4 5% 7% 36%	4398
	21st to end	Day	18% 8% 2 6% 5% 4 4 4 5% 7% 37%	5176
June	1st to 10th	Day	20% 10% 3 7% 6% 5% 5% 4 5% 6% 31%	2850
	11th to 20th	Day	16% 8% 3 7% 5% 4 4 4 6% 7% 36%	2850
	21st to end	Day	19% 7% 3 8% 5% 6% 4 4 6% 7% 32%	2850
July	1st to 10th	Day	18% 7% 3 7% 5% 5% 5% 4 7% 8% 33%	4760
	11th to 20th	Day	13% 6% 2 7% 5% 5% 5% 4 7% 9% 37%	4760
	21st to end	Day	15% 7% 2 7% 5% 4 4 4 6% 8% 38%	4935
August	1st to 10th	Day	11% 7% 3 7% 5% 5% 5% 5% 6% 8% 38%	4104
	11th to 20th	Day	18% 7% 3 6% 4 4 5% 4 5% 8% 37%	4044
	21st to end	Day	17% 6% 2 6% 4 4 4 4 5% 7% 40%	4532
September	1st to 10th	Day	19% 9% 3 6% 4 5% 5% 4 5% 6% 33%	2300
	11th to 20th	Day	20% 8% 3 7% 4 4 3 4 6% 8% 35%	2090
	21st to end	Day	22% 12% 2 7% 4 4 3 4 4 6% 33%	2090
October	1st to 10th	Day	22% 16% 3 7% 4 3 3 2 4 7% 28%	1933
	11th to 20th	Day	24% 19% 4 9% 4 4 4 3 4 5% 20%	1900
	21st to end	Day	25% 24% 5% 8% 5% 3 3 2 3 5% 15%	1912
November	1st to 10th	Day	22% 18% 4 11% 4 4 3 3 4 6% 20%	1640
	11th to 20th	Day	19% 21% 6% 14% 7% 5% 4 3 4 4 13%	1600
	21st to end	Day	20% 23% 8% 15% 7% 5% 4 2 2 4 10%	1600
December	1st to 10th	Day	13% 21% 12% 22% 8% 4 3 2 3 4 7%	2322
	11th to 20th	Day	14% 22% 5% 15% 7% 5% 4 3 3 5% 17%	2621
	21st to end	Day	20% 22% 10% 16% 6% 4 3 3 4 3 11%	3476
January	1st to 10th	Night	10% 18% 8% 19% 10% 9% 6% 3 4 4 10%	6808
	11th to 20th	Night	11% 17% 6% 15% 9% 7% 6% 4 4 5% 16%	6572
	21st to end	Night	8% 17% 10% 16% 7% 6% 7% 3 5% 5% 16%	6927
February	1st to 10th	Night	10% 14% 4 14% 10% 7% 5% 4 5% 6% 20%	2600
	11th to 20th	Night	10% 17% 6% 13% 9% 7% 6% 3 4 4 21%	2533
	21st to end	Night	11% 17% 7% 12% 8% 7% 5% 4 5% 5% 20%	2004
March	1st to 10th	Night	16% 16% 3 9% 5% 5% 4 2 4 5% 32%	3595
	11th to 20th	Night	12% 17% 7% 14% 6% 4 3 2 3 5% 26%	3479
	21st to end	Night	13% 11% 6% 13% 7% 6% 5% 3 4 5% 28%	3817
April	1st to 10th	Night	19% 14% 5% 10% 4 4 4 3 5% 5% 27%	1919
	11th to 20th	Night	19% 12% 3 8% 5% 3 3 3 5% 6% 32%	1687
	21st to end	Night	18% 12% 3 7% 5% 4 3 3 5% 5% 35%	1710
May	1st to 10th	Night	15% 13% 4 7% 4 4 4 2 4 5% 37%	2806
	11th to 20th	Night	14% 8% 2 9% 5% 5% 5% 4 6% 9% 34%	2495
	21st to end	Night	16% 9% 3 6% 3 4 4 3 5% 8% 39%	2407
June	1st to 10th	Night	18% 9% 2 7% 5% 6% 4 4 5% 8% 33%	1330
	11th to 20th	Night	17% 8% 2 7% 5% 4 3 5% 7% 7% 36%	1330
	21st to end	Night	16% 7% 2 6% 5% 4 4 4 6% 8% 38%	1330
July	1st to 10th	Night	16% 7% 2 6% 4 5% 4 4 6% 7% 40%	2210
	11th to 20th	Night	12% 7% 2 7% 5% 5% 5% 4 6% 8% 38%	2210
	21st to end	Night	15% 6% 2 6% 4 3 4 4 6% 7% 44%	2609
August	1st to 10th	Night	9% 6% 2 8% 6% 5% 6% 5% 6% 8% 39%	2825
	11th to 20th	Night	16% 9% 3 5% 3 4 4 3 5% 7% 41%	2785
	21st to end	Night	14% 6% 2 5% 4 4 4 3 4 6% 48%	3124
September	1st to 10th	Night	19% 8% 2 6% 4 4 3 3 4 6% 41%	1858
	11th to 20th	Night	17% 9% 3 6% 3 3 3 3 5% 5% 42%	2090
	21st to end	Night	19% 10% 2 6% 4 5% 4 3 5% 6% 36%	2090
October	1st to 10th	Night	20% 13% 3 7% 5% 4 3 3 4 6% 32%	2247
	11th to 20th	Night	26% 16% 4 7% 5% 4 4 3 4 5% 23%	2280
	21st to end	Night	24% 22% 4 8% 4 4 4 3 3 5% 19%	2684
November	1st to 10th	Night	19% 17% 5% 9% 5% 4 5% 3 5% 5% 22%	2656
	11th to 20th	Night	20% 17% 5% 13% 8% 5% 4 3 4 4 16%	2800
	21st to end	Night	20% 21% 7% 15% 8% 5% 4 3 3 3 10%	2800
December	1st to 10th	Night	13% 25% 10% 18% 8% 6% 3 2 3 3 8%	4862
	11th to 20th	Night	13% 21% 6% 14% 8% 6% 4 3 4 5% 14%	5586
	21st to end	Night	21% 22% 6% 14% 6% 4 3 3 4 4 12%	7502

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	78% 5% 7% 6% 2 2	3159
	11th to 20th	Day	68% 5% 8% 13% 7%	3360
	21st to end	Day	71% 5% 5% 13% 5%	4046
February	1st to 10th	Day	65% 6% 8% 14% 7%	1800
	11th to 20th	Day	62% 5% 10% 13% 10% 1	1762
	21st to end	Day	63% 4 7% 16% 9% 1	1541
March	1st to 10th	Day	57% 7% 13% 16% 7% 1	3248
	11th to 20th	Day	61% 6% 10% 15% 7% 1	3480
	21st to end	Day	59% 6% 8% 14% 10% 2	3815
April	1st to 10th	Day	62% 6% 8% 14% 8% 1	2276
	11th to 20th	Day	56% 5% 8% 20% 9% 2	2442
	21st to end	Day	52% 5% 9% 16% 14% 2	2470
May	1st to 10th	Day	47% 7% 11% 21% 12% 1	4147
	11th to 20th	Day	43% 10% 14% 21% 11% 1	4402
	21st to end	Day	43% 9% 12% 18% 14% 4	5176
June	1st to 10th	Day	51% 8% 11% 20% 10%	2850
	11th to 20th	Day	46% 7% 12% 21% 12% 1	2850
	21st to end	Day	51% 8% 12% 17% 12%	2850
July	1st to 10th	Day	47% 7% 16% 22% 8%	4686
	11th to 20th	Day	39% 8% 19% 25% 8%	4679
	21st to end	Day	43% 7% 11% 30% 9%	4778
August	1st to 10th	Day	41% 8% 15% 26% 9%	4091
	11th to 20th	Day	44% 9% 15% 26% 7%	4083
	21st to end	Day	42% 7% 14% 27% 7% 2	4531
September	1st to 10th	Day	49% 8% 15% 18% 9% 1	2300
	11th to 20th	Day	48% 8% 16% 22% 6%	2090
	21st to end	Day	53% 7% 12% 19% 8%	2090
October	1st to 10th	Day	52% 5% 14% 22% 7%	3206
	11th to 20th	Day	59% 4 11% 18% 7%	3140
	21st to end	Day	70% 5% 12% 9% 4	3124
November	1st to 10th	Day	66% 7% 11% 11% 5%	1640
	11th to 20th	Day	76% 6% 7% 8% 3	1600
	21st to end	Day	81% 5% 8% 6% 1	1600
December	1st to 10th	Day	83% 4 6% 5% 2	2322
	11th to 20th	Day	70% 5% 11% 12% 3	2621
	21st to end	Day	79% 3 3 10% 4	3476
January	1st to 10th	Night	79% 5% 6% 7% 3 1	6808
	11th to 20th	Night	71% 5% 7% 11% 6%	6618
	21st to end	Night	70% 5% 6% 12% 7%	6927
February	1st to 10th	Night	64% 5% 10% 12% 8% 1	2600
	11th to 20th	Night	66% 4 9% 14% 6%	2535
	21st to end	Night	65% 6% 8% 13% 7% 1	2004
March	1st to 10th	Night	55% 6% 12% 18% 9% 1	3605
	11th to 20th	Night	61% 6% 8% 16% 8% 1	3480
	21st to end	Night	57% 8% 8% 13% 12% 2	3817
April	1st to 10th	Night	57% 6% 9% 17% 11% 1	1919
	11th to 20th	Night	53% 6% 8% 19% 13% 2	1687
	21st to end	Night	51% 4 10% 17% 15% 3	1710
May	1st to 10th	Night	47% 8% 8% 21% 15% 1	2813
	11th to 20th	Night	42% 9% 12% 26% 9% 1	2496
	21st to end	Night	42% 7% 13% 21% 13% 3	2408
June	1st to 10th	Night	48% 8% 12% 18% 11% 2	1330
	11th to 20th	Night	44% 8% 10% 20% 16% 1	1330
	21st to end	Night	43% 8% 13% 22% 12% 1	1330
July	1st to 10th	Night	42% 7% 14% 28% 9%	2175
	11th to 20th	Night	41% 8% 16% 26% 8%	2168
	21st to end	Night	40% 7% 15% 26% 13%	2526
August	1st to 10th	Night	40% 9% 14% 31% 6%	2814
	11th to 20th	Night	42% 6% 17% 28% 5%	2812
	21st to end	Night	36% 7% 12% 32% 12% 1	3124
September	1st to 10th	Night	45% 6% 16% 23% 9% 1	1858
	11th to 20th	Night	44% 7% 17% 25% 7%	2090
	21st to end	Night	48% 8% 15% 21% 7%	2090
October	1st to 10th	Night	49% 7% 12% 25% 8%	3754
	11th to 20th	Night	58% 6% 11% 19% 6%	3779
	21st to end	Night	63% 6% 16% 12% 3	4422
November	1st to 10th	Night	62% 7% 13% 13% 4	2656
	11th to 20th	Night	71% 6% 10% 9% 3	2800
	21st to end	Night	80% 6% 8% 5% 2	2800
December	1st to 10th	Night	83% 4 6% 6% 2	4862
	11th to 20th	Night	73% 5% 7% 10% 5%	5585
	21st to end	Night	76% 4 5% 11% 4	7502

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	21% 18% 36% 19% 5% 2	200
	11th to 20th	Day	19% 13% 36% 27% 4 2	243
	21st to end	Day	21% 14% 35% 25% 5% 1	330
February	1st to 10th	Day	20% 27% 35% 14% 3 1	300
	11th to 20th	Day	20% 22% 40% 14% 2 2	300
	21st to end	Day	21% 33% 37% 9% 1	237
March	1st to 10th	Day	20% 24% 37% 17% 3	346
	11th to 20th	Day	22% 22% 32% 17% 6% 1	460
	21st to end	Day	26% 16% 34% 18% 5%	506
April	1st to 10th	Day	27% 15% 33% 20% 6%	460
	11th to 20th	Day	29% 18% 26% 17% 5% 3	452
	21st to end	Day	30% 16% 26% 17% 8% 2	460
May	1st to 10th	Day	22% 16% 33% 19% 8% 2	463
	11th to 20th	Day	19% 16% 36% 18% 8% 3	487
	21st to end	Day	20% 17% 31% 23% 8%	725
June	1st to 10th	Day	21% 14% 35% 21% 7% 2	680
	11th to 20th	Day	21% 15% 32% 23% 7% 1	680
	21st to end	Day	20% 12% 29% 24% 13% 2	680
July	1st to 10th	Day	15% 12% 35% 25% 12% 1	671
	11th to 20th	Day	15% 10% 32% 28% 12% 2	668
	21st to end	Day	17% 9% 30% 30% 10% 4	730
August	1st to 10th	Day	14% 12% 28% 28% 14% 4	486
	11th to 20th	Day	16% 7% 26% 26% 16% 9%	479
	21st to end	Day	21% 11% 30% 20% 13% 6%	539
September	1st to 10th	Day	22% 10% 31% 23% 10% 4	490
	11th to 20th	Day	22% 12% 27% 24% 11% 4	490
	21st to end	Day	28% 13% 25% 21% 10% 2	490
October	1st to 10th	Day	28% 17% 27% 18% 8% 2	490
	11th to 20th	Day	31% 18% 33% 15% 2 1	490
	21st to end	Day	34% 20% 31% 13% 1 1	361
November	1st to 10th	Day	31% 19% 37% 12% 1	238
	11th to 20th	Day	30% 26% 29% 13% 3	200
	21st to end	Day	34% 21% 35% 10% 1 1	200
December	1st to 10th	Day	18% 22% 37% 17% 6% 1	200
	11th to 20th	Day	28% 17% 40% 11% 4 1	200
	21st to end	Day	31% 18% 31% 15% 5% 1	220
January	1st to 10th	Night	22% 12% 41% 19% 5% 1	1000
	11th to 20th	Night	25% 13% 33% 22% 7%	1000
	21st to end	Night	19% 12% 30% 28% 10% 1	1070
February	1st to 10th	Night	17% 16% 37% 24% 6%	800
	11th to 20th	Night	20% 16% 36% 21% 7% 1	783
	21st to end	Night	21% 16% 38% 21% 4	647
March	1st to 10th	Night	19% 19% 33% 25% 4	760
	11th to 20th	Night	23% 19% 34% 19% 6% 1	760
	21st to end	Night	19% 14% 37% 23% 6% 1	836
April	1st to 10th	Night	25% 17% 29% 24% 5%	686
	11th to 20th	Night	26% 13% 27% 26% 8% 1	563
	21st to end	Night	24% 11% 31% 23% 11%	570
May	1st to 10th	Night	20% 9% 34% 29% 8%	556
	11th to 20th	Night	20% 12% 30% 29% 7% 2	374
	21st to end	Night	20% 12% 31% 30% 6%	411
June	1st to 10th	Night	21% 8% 31% 33% 7%	380
	11th to 20th	Night	21% 10% 30% 29% 10% 1	380
	21st to end	Night	19% 6% 29% 36% 11%	380
July	1st to 10th	Night	16% 6% 34% 32% 12%	370
	11th to 20th	Night	14% 8% 30% 35% 13%	368
	21st to end	Night	18% 4 25% 38% 14% 1	530
August	1st to 10th	Night	16% 4 28% 34% 17% 1	567
	11th to 20th	Night	16% 6% 23% 30% 23% 1	564
	21st to end	Night	20% 7% 30% 25% 15% 2	627
September	1st to 10th	Night	21% 8% 28% 26% 15% 2	696
	11th to 20th	Night	22% 10% 27% 25% 14% 2	760
	21st to end	Night	24% 8% 26% 28% 12% 1	760
October	1st to 10th	Night	27% 11% 29% 24% 7% 1	760
	11th to 20th	Night	34% 15% 29% 17% 5% 1	760
	21st to end	Night	35% 15% 27% 20% 3	836
November	1st to 10th	Night	28% 15% 36% 17% 4 1	780
	11th to 20th	Night	31% 15% 30% 19% 5%	800
	21st to end	Night	29% 15% 36% 16% 3 1	800
December	1st to 10th	Night	25% 16% 32% 21% 5% 1	965
	11th to 20th	Night	26% 17% 33% 18% 6% 1	1000
	21st to end	Night	28% 15% 30% 20% 6% 1	1100

Page generated at 2025-02-22 06:51:39. Version ac07

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