Gold River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gold River clear sky chart from 2005-11-06 to 2024-11-12.

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	24% 15% 3 7% 4 4 3 3 4 5% 28%	105583
	Night	28% 17% 4 7% 4 3 3 2 4 4 24%	102212
Transparency	Day	60% 5% 10% 15% 8% 2	105323
	Night	64% 5% 9% 13% 8% 2	102118
Seeing	Day	34% 14% 24% 19% 8% 2	15912
	Night	37% 8% 21% 22% 11% 1	23743

By Month

Percentage Cloud Cover NW (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	36% 28% 3 4 3 2 2 2 3 3 12%	2219
	11th to 20th	Day	29% 16% 4 7% 3 2 2 2 4 6% 24%	2199
	21st to end	Day	46% 21% 4 6% 4 3 2 2 2 2 9%	2675
February	1st to 10th	Day	32% 21% 5% 6% 3 3 4 3 4 4 14%	1688
	11th to 20th	Day	24% 25% 4 8% 3 3 2 1 2 4 24%	1665
	21st to end	Day	23% 27% 4 7% 4 4 4 3 3 3 18%	1422
March	1st to 10th	Day	19% 26% 5% 10% 5% 5% 3 3 3 5% 17%	3276
	11th to 20th	Day	23% 25% 4 7% 4 3 3 2 3 3 22%	3490
	21st to end	Day	23% 23% 4 10% 5% 5% 4 3 3 4 16%	3825
April	1st to 10th	Day	28% 26% 5% 9% 4 4 3 2 2 4 14%	2301
	11th to 20th	Day	26% 24% 4 8% 4 3 3 2 4 4 18%	2438
	21st to end	Day	30% 22% 4 8% 4 4 3 2 3 3 16%	2470
May	1st to 10th	Day	20% 16% 4 8% 5% 4 4 3 4 5% 28%	4321
	11th to 20th	Day	16% 13% 4 9% 6% 5% 5% 4 6% 8% 25%	4497
	21st to end	Day	29% 16% 4 10% 5% 4 3 3 3 4 18%	5161
June	1st to 10th	Day	30% 15% 4 8% 5% 4 4 2 4 5% 19%	2850
	11th to 20th	Day	29% 14% 4 8% 5% 4 3 3 5% 6% 19%	2850
	21st to end	Day	27% 11% 3 6% 4 4 4 3 4 6% 27%	2850
July	1st to 10th	Day	11% 6% 2 5% 3 3 3 2 4 4 59%	4740
	11th to 20th	Day	10% 5% 1 3 2 3 3 3 4 6% 60%	4740
	21st to end	Day	16% 8% 3 7% 4 4 3 3 5% 7% 39%	5138
August	1st to 10th	Day	8% 3 1 3 2 2 3 3 6% 8% 62%	4198
	11th to 20th	Day	17% 12% 4 8% 4 4 4 4 6% 6% 31%	4026
	21st to end	Day	19% 7% 2 6% 4 4 4 4 6% 7% 37%	4521
September	1st to 10th	Day	17% 7% 2 7% 4 3 4 3 5% 5% 42%	2341
	11th to 20th	Day	23% 10% 3 7% 4 3 4 3 3 5% 36%	2121
	21st to end	Day	29% 9% 3 6% 3 4 4 2 4 6% 31%	2090
October	1st to 10th	Day	32% 14% 4 9% 3 3 3 3 3 4 22%	3194
	11th to 20th	Day	34% 13% 3 7% 3 3 4 3 4 5% 20%	3161
	21st to end	Day	31% 16% 4 8% 5% 5% 4 3 5% 4 16%	3100
November	1st to 10th	Day	40% 18% 4 7% 4 2 3 2 2 4 13%	1568
	11th to 20th	Day	38% 20% 4 5% 4 3 3 2 2 2 16%	1528
	21st to end	Day	38% 19% 3 6% 3 3 3 2 3 3 18%	1463
December	1st to 10th	Day	29% 16% 4 8% 4 4 3 2 2 5% 24%	1330
	11th to 20th	Day	40% 19% 4 6% 3 3 3 2 2 3 16%	1685
	21st to end	Day	40% 25% 4 7% 3 2 2 2 2 2 10%	2442
January	1st to 10th	Night	35% 30% 4 7% 3 3 2 2 2 2 11%	4726
	11th to 20th	Night	32% 12% 3 5% 4 3 4 3 4 6% 24%	4699
	21st to end	Night	49% 21% 3 5% 3 2 2 1 2 3 9%	4986
February	1st to 10th	Night	33% 18% 5% 8% 4 3 3 2 3 4 17%	2491
	11th to 20th	Night	24% 23% 4 7% 3 3 3 3 3 4 24%	2402
	21st to end	Night	24% 24% 5% 7% 4 3 3 3 4 3 20%	2030
March	1st to 10th	Night	19% 23% 5% 9% 4 4 4 3 5% 4 20%	3593
	11th to 20th	Night	21% 24% 5% 8% 4 3 3 2 4 4 23%	3489
	21st to end	Night	24% 24% 5% 7% 4 3 3 3 3 4 19%	3828
April	1st to 10th	Night	23% 25% 5% 7% 5% 4 4 3 4 4 17%	1877
	11th to 20th	Night	23% 23% 4 6% 4 4 4 4 3 4 21%	1691
	21st to end	Night	28% 19% 4 8% 5% 4 3 3 3 3 20%	1710
May	1st to 10th	Night	17% 16% 4 7% 5% 4 3 3 4 5% 33%	2641
	11th to 20th	Night	16% 12% 3 6% 5% 4 4 4 5% 7% 33%	2394
	21st to end	Night	26% 18% 2 7% 5% 3 3 2 3 4 26%	2414
June	1st to 10th	Night	25% 15% 4 7% 5% 4 4 3 4 5% 23%	1330
	11th to 20th	Night	22% 16% 5% 8% 4 5% 5% 4 5% 5% 22%	1330
	21st to end	Night	22% 10% 3 6% 5% 3 3 3 6% 6% 32%	1330
July	1st to 10th	Night	9% 7% 3 5% 3 2 3 2 4 5% 57%	2220
	11th to 20th	Night	7% 5% 2 4 2 2 3 2 4 6% 63%	2220
	21st to end	Night	16% 9% 3 5% 4 3 4 3 4 6% 43%	2414
August	1st to 10th	Night	6% 5% 1 3 2 2 3 2 4 5% 65%	2736
	11th to 20th	Night	14% 13% 4 8% 5% 4 5% 4 5% 7% 32%	2812
	21st to end	Night	17% 11% 3 7% 4 4 4 3 5% 5% 38%	3146
September	1st to 10th	Night	15% 9% 2 5% 3 4 4 4 5% 6% 43%	1838
	11th to 20th	Night	21% 10% 4 7% 4 3 3 2 4 5% 37%	2057
	21st to end	Night	30% 11% 3 6% 4 2 3 2 3 5% 31%	2090
October	1st to 10th	Night	33% 14% 4 8% 4 4 4 3 4 4 19%	3785
	11th to 20th	Night	37% 14% 4 8% 4 4 3 2 4 5% 17%	3777
	21st to end	Night	30% 15% 4 8% 5% 5% 4 3 4 4 20%	4454
November	1st to 10th	Night	42% 16% 4 7% 4 3 3 2 2 3 12%	2730
	11th to 20th	Night	37% 22% 4 7% 3 2 2 2 2 3 16%	2674
	21st to end	Night	35% 18% 3 8% 4 3 3 1 3 2 18%	2714
December	1st to 10th	Night	29% 18% 3 6% 4 4 3 2 4 5% 21%	2850
	11th to 20th	Night	41% 20% 3 6% 4 3 3 2 2 3 14%	3520
	21st to end	Night	44% 22% 3 7% 4 2 2 1 2 2 10%	5214

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% 4 5% 7% 5% 2	2219
	11th to 20th	Day	63% 4 7% 10% 12% 4	2220
	21st to end	Day	85% 2 3 6% 3 1	2675
February	1st to 10th	Day	75% 4 5% 7% 6% 3	1688
	11th to 20th	Day	68% 2 7% 11% 10% 2	1674
	21st to end	Day	72% 4 7% 9% 5% 3	1422
March	1st to 10th	Day	70% 5% 5% 10% 5% 4	3276
	11th to 20th	Day	69% 3 5% 11% 11% 1	3490
	21st to end	Day	72% 7% 9% 8% 2 2	3825
April	1st to 10th	Day	77% 4 7% 8% 4 1	2301
	11th to 20th	Day	71% 5% 6% 10% 8% 2	2438
	21st to end	Day	74% 4 5% 10% 6%	2470
May	1st to 10th	Day	58% 7% 10% 19% 6%	4321
	11th to 20th	Day	54% 11% 13% 17% 4	4500
	21st to end	Day	70% 6% 7% 8% 7% 1	5162
June	1st to 10th	Day	69% 6% 8% 9% 6% 1	2850
	11th to 20th	Day	66% 7% 11% 12% 4	2850
	21st to end	Day	60% 6% 12% 15% 6%	2850
July	1st to 10th	Day	30% 4 9% 21% 21% 14%	4666
	11th to 20th	Day	25% 7% 13% 36% 19%	4659
	21st to end	Day	42% 7% 17% 22% 11% 1	4976
August	1st to 10th	Day	22% 5% 14% 42% 16% 1	4180
	11th to 20th	Day	51% 9% 17% 13% 8% 1	4065
	21st to end	Day	45% 7% 20% 20% 8%	4520
September	1st to 10th	Day	44% 5% 13% 24% 10% 4	2341
	11th to 20th	Day	53% 4 11% 16% 14% 2	2121
	21st to end	Day	56% 5% 11% 14% 11% 2	2090
October	1st to 10th	Day	67% 5% 9% 11% 8% 1	3194
	11th to 20th	Day	66% 4 9% 14% 6%	3161
	21st to end	Day	67% 8% 8% 10% 6% 1	3100
November	1st to 10th	Day	78% 3 5% 8% 4 1	1568
	11th to 20th	Day	77% 3 6% 6% 6% 3	1528
	21st to end	Day	75% 2 5% 7% 8% 3	1463
December	1st to 10th	Day	67% 4 9% 10% 7% 4	1330
	11th to 20th	Day	76% 3 6% 7% 5% 3	1688
	21st to end	Day	83% 2 5% 6% 3 2	2442
January	1st to 10th	Night	82% 3 4 5% 4 2	4726
	11th to 20th	Night	61% 5% 6% 11% 13% 4	4740
	21st to end	Night	83% 3 3 5% 4 2	4986
February	1st to 10th	Night	74% 4 4 7% 7% 3	2491
	11th to 20th	Night	67% 3 6% 11% 10% 3	2404
	21st to end	Night	70% 5% 7% 12% 5% 2	2030
March	1st to 10th	Night	64% 6% 7% 11% 8% 3	3593
	11th to 20th	Night	67% 3 5% 13% 9% 2	3490
	21st to end	Night	71% 5% 9% 10% 5% 1	3828
April	1st to 10th	Night	71% 7% 8% 10% 4	1877
	11th to 20th	Night	67% 5% 6% 11% 11% 1	1691
	21st to end	Night	70% 3 6% 12% 7% 1	1710
May	1st to 10th	Night	51% 9% 11% 20% 8%	2641
	11th to 20th	Night	48% 10% 18% 16% 6% 1	2394
	21st to end	Night	64% 7% 9% 14% 5% 2	2414
June	1st to 10th	Night	64% 6% 11% 11% 6% 2	1330
	11th to 20th	Night	63% 8% 12% 12% 5%	1330
	21st to end	Night	53% 7% 17% 15% 8% 1	1330
July	1st to 10th	Night	31% 4 11% 16% 30% 8%	2185
	11th to 20th	Night	23% 6% 17% 41% 13% 1	2178
	21st to end	Night	41% 8% 16% 25% 9% 1	2337
August	1st to 10th	Night	22% 4 12% 41% 20% 1	2729
	11th to 20th	Night	48% 11% 17% 14% 9% 1	2839
	21st to end	Night	46% 8% 18% 22% 7%	3146
September	1st to 10th	Night	41% 7% 14% 23% 13% 2	1838
	11th to 20th	Night	51% 5% 11% 14% 17% 2	2057
	21st to end	Night	57% 5% 12% 13% 10% 3	2090
October	1st to 10th	Night	68% 6% 8% 10% 7% 1	3785
	11th to 20th	Night	71% 4 8% 12% 5%	3777
	21st to end	Night	66% 7% 8% 11% 7% 1	4454
November	1st to 10th	Night	79% 4 6% 6% 5% 1	2730
	11th to 20th	Night	77% 3 5% 7% 5% 4	2674
	21st to end	Night	74% 3 5% 7% 7% 4	2714
December	1st to 10th	Night	67% 4 8% 11% 8% 3	2850
	11th to 20th	Night	79% 3 4 6% 5% 2	3516
	21st to end	Night	82% 3 4 5% 3 2	5214

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	51% 13% 19% 10% 6% 2	180
	11th to 20th	Day	46% 13% 22% 12% 7%	180
	21st to end	Day	47% 11% 20% 13% 9% 1	340
February	1st to 10th	Day	46% 13% 26% 13% 2	370
	11th to 20th	Day	41% 15% 28% 11% 5%	365
	21st to end	Day	47% 14% 23% 12% 3	307
March	1st to 10th	Day	39% 16% 23% 15% 5% 2	411
	11th to 20th	Day	40% 16% 23% 15% 7%	460
	21st to end	Day	45% 13% 25% 12% 4 1	506
April	1st to 10th	Day	46% 20% 19% 11% 3	460
	11th to 20th	Day	40% 16% 24% 13% 5% 2	452
	21st to end	Day	48% 18% 17% 11% 4 1	460
May	1st to 10th	Day	31% 19% 26% 17% 6% 1	463
	11th to 20th	Day	32% 13% 27% 18% 8% 2	555
	21st to end	Day	28% 16% 31% 17% 6% 1	735
June	1st to 10th	Day	40% 18% 21% 15% 5% 1	680
	11th to 20th	Day	35% 22% 20% 16% 5% 1	680
	21st to end	Day	29% 14% 25% 23% 8% 2	680
July	1st to 10th	Day	23% 12% 27% 28% 8% 2	671
	11th to 20th	Day	18% 14% 29% 26% 10% 3	668
	21st to end	Day	17% 10% 24% 32% 13% 4	739
August	1st to 10th	Day	16% 6% 20% 37% 14% 6%	531
	11th to 20th	Day	13% 7% 27% 32% 18% 4	477
	21st to end	Day	23% 13% 27% 23% 10% 3	539
September	1st to 10th	Day	23% 12% 30% 22% 11% 1	490
	11th to 20th	Day	33% 11% 22% 21% 10% 2	490
	21st to end	Day	35% 14% 21% 19% 10% 1	490
October	1st to 10th	Day	34% 13% 24% 19% 6% 3	490
	11th to 20th	Day	46% 10% 20% 13% 9% 2	490
	21st to end	Day	47% 12% 21% 10% 8% 2	433
November	1st to 10th	Day	43% 14% 23% 15% 6%	200
	11th to 20th	Day	46% 14% 13% 16% 9% 3	182
	21st to end	Day	53% 12% 12% 9% 8% 6%	180
December	1st to 10th	Day	39% 12% 19% 15% 12% 2	180
	11th to 20th	Day	43% 12% 18% 14% 10% 3	180
	21st to end	Day	48% 11% 20% 17% 4 1	198
January	1st to 10th	Night	52% 12% 20% 13% 4	850
	11th to 20th	Night	45% 9% 24% 16% 6%	850
	21st to end	Night	48% 8% 21% 17% 5% 1	935
February	1st to 10th	Night	44% 9% 27% 17% 3	769
	11th to 20th	Night	40% 8% 24% 24% 5%	744
	21st to end	Night	39% 11% 26% 16% 7% 1	628
March	1st to 10th	Night	36% 13% 23% 19% 8%	760
	11th to 20th	Night	42% 11% 21% 20% 6%	760
	21st to end	Night	44% 11% 18% 18% 7% 1	836
April	1st to 10th	Night	37% 9% 24% 22% 6% 1	689
	11th to 20th	Night	34% 10% 26% 21% 9%	563
	21st to end	Night	39% 6% 24% 23% 7%	570
May	1st to 10th	Night	28% 7% 20% 27% 17% 1	442
	11th to 20th	Night	27% 6% 18% 30% 18% 1	374
	21st to end	Night	26% 4 21% 33% 15%	411
June	1st to 10th	Night	32% 7% 17% 28% 15% 1	380
	11th to 20th	Night	28% 9% 25% 23% 14% 1	380
	21st to end	Night	24% 5% 20% 31% 17% 2	380
July	1st to 10th	Night	17% 4 18% 34% 26% 2	370
	11th to 20th	Night	15% 4 16% 35% 29% 1	368
	21st to end	Night	14% 4 13% 30% 36% 3	416
August	1st to 10th	Night	14% 4 9% 30% 37% 7%	538
	11th to 20th	Night	15% 3 10% 40% 30% 3	564
	21st to end	Night	23% 5% 19% 31% 21% 1	627
September	1st to 10th	Night	19% 5% 19% 34% 20% 3	698
	11th to 20th	Night	25% 6% 17% 26% 23% 4	760
	21st to end	Night	36% 6% 20% 26% 11% 1	760
October	1st to 10th	Night	35% 4 21% 25% 13% 2	760
	11th to 20th	Night	43% 5% 20% 19% 11% 2	760
	21st to end	Night	44% 8% 24% 18% 5% 2	836
November	1st to 10th	Night	52% 7% 23% 16% 2	780
	11th to 20th	Night	50% 9% 23% 14% 3	764
	21st to end	Night	47% 10% 23% 13% 6% 1	786
December	1st to 10th	Night	40% 9% 22% 20% 7% 1	850
	11th to 20th	Night	51% 8% 22% 15% 4	850
	21st to end	Night	50% 12% 23% 14% 1	935

Page generated at 2024-11-08 19:45:34. Version ac07

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