Prince George
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prince George clear sky chart from 2005-11-06 to 2024-11-04.

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	10% 11% 4 9% 6% 5% 5% 4 6% 7% 32%	105672
	Night	12% 13% 4 9% 6% 6% 6% 4 6% 7% 29%	101906
Transparency	Day	47% 10% 16% 19% 7%	105407
	Night	52% 10% 14% 17% 7% 1	101817
Seeing	Day	16% 10% 23% 26% 19% 6%	16442
	Night	20% 8% 20% 31% 18% 3	24214

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	9% 19% 7% 15% 8% 6% 6% 4 4 5% 16%	2063
	11th to 20th	Day	12% 17% 5% 9% 5% 3 4 4 5% 6% 29%	2199
	21st to end	Day	12% 21% 6% 13% 7% 6% 6% 4 6% 5% 14%	2442
February	1st to 10th	Day	15% 17% 5% 9% 6% 4 4 3 6% 7% 24%	1534
	11th to 20th	Day	11% 15% 5% 11% 7% 6% 5% 4 6% 6% 24%	1665
	21st to end	Day	6% 17% 5% 10% 8% 5% 5% 3 6% 6% 29%	1413
March	1st to 10th	Day	6% 14% 5% 13% 6% 5% 6% 4 6% 9% 26%	3117
	11th to 20th	Day	7% 12% 4 9% 7% 6% 6% 5% 8% 9% 27%	3490
	21st to end	Day	6% 12% 3 8% 5% 5% 6% 4 6% 7% 38%	3973
April	1st to 10th	Day	7% 12% 5% 12% 9% 6% 6% 5% 7% 7% 26%	2280
	11th to 20th	Day	10% 13% 5% 9% 7% 7% 6% 5% 6% 6% 26%	2426
	21st to end	Day	12% 12% 4 9% 6% 6% 5% 4 6% 7% 29%	2649
May	1st to 10th	Day	8% 9% 4 10% 6% 5% 5% 4 7% 10% 33%	4420
	11th to 20th	Day	10% 11% 4 10% 7% 7% 6% 6% 7% 7% 24%	4582
	21st to end	Day	12% 11% 4 11% 7% 7% 6% 5% 6% 7% 24%	5406
June	1st to 10th	Day	11% 8% 3 9% 7% 6% 7% 5% 7% 8% 29%	3040
	11th to 20th	Day	14% 8% 3 9% 7% 7% 6% 4 7% 8% 27%	3040
	21st to end	Day	11% 8% 4 7% 6% 5% 6% 6% 7% 7% 33%	3040
July	1st to 10th	Day	8% 5% 2 5% 4 4 5% 4 6% 8% 49%	5060
	11th to 20th	Day	6% 5% 2 4 3 3 5% 4 6% 9% 52%	4776
	21st to end	Day	9% 6% 3 7% 6% 5% 6% 6% 7% 10% 36%	5138
August	1st to 10th	Day	4 4 1 4 3 3 4 3 6% 9% 59%	4506
	11th to 20th	Day	8% 5% 2 7% 5% 5% 5% 5% 7% 9% 43%	4255
	21st to end	Day	11% 8% 3 9% 5% 6% 6% 5% 6% 7% 34%	4521
September	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 4 6% 8% 40%	2282
	11th to 20th	Day	10% 6% 3 8% 5% 6% 6% 5% 7% 8% 37%	2280
	21st to end	Day	16% 9% 3 9% 7% 5% 6% 4 6% 7% 28%	2003
October	1st to 10th	Day	16% 13% 4 10% 6% 6% 5% 4 5% 6% 24%	3180
	11th to 20th	Day	17% 13% 3 9% 5% 6% 6% 4 6% 7% 25%	3140
	21st to end	Day	12% 11% 4 9% 6% 5% 6% 4 6% 8% 30%	2854
November	1st to 10th	Day	19% 15% 4 11% 5% 4 4 4 5% 4 24%	1512
	11th to 20th	Day	12% 17% 5% 12% 9% 6% 6% 4 5% 6% 17%	1508
	21st to end	Day	14% 20% 5% 10% 7% 6% 6% 7% 5% 4 17%	1206
December	1st to 10th	Day	13% 16% 5% 14% 8% 5% 6% 4 5% 5% 19%	1140
	11th to 20th	Day	19% 20% 5% 10% 7% 4 5% 4 4 6% 16%	1442
	21st to end	Day	8% 16% 5% 10% 8% 7% 7% 4 6% 7% 22%	2090
January	1st to 10th	Night	11% 17% 5% 13% 8% 7% 7% 5% 5% 5% 16%	4910
	11th to 20th	Night	12% 16% 4 10% 6% 5% 5% 3 4 6% 29%	4699
	21st to end	Night	19% 22% 5% 11% 6% 5% 5% 3 4 4 13%	5214
February	1st to 10th	Night	14% 20% 5% 9% 7% 5% 4 4 5% 5% 23%	2644
	11th to 20th	Night	12% 15% 5% 10% 7% 5% 5% 4 5% 7% 25%	2402
	21st to end	Night	8% 15% 5% 11% 6% 4 5% 4 6% 6% 30%	2041
March	1st to 10th	Night	5% 16% 4 11% 6% 6% 7% 4 7% 9% 24%	3754
	11th to 20th	Night	8% 12% 5% 9% 7% 7% 7% 5% 8% 7% 25%	3489
	21st to end	Night	7% 10% 3 6% 5% 4 4 4 6% 7% 44%	3679
April	1st to 10th	Night	9% 13% 4 9% 6% 5% 5% 4 6% 7% 29%	1900
	11th to 20th	Night	9% 12% 3 8% 6% 7% 7% 5% 7% 7% 28%	1701
	21st to end	Night	12% 11% 4 8% 5% 6% 6% 5% 6% 6% 32%	1530
May	1st to 10th	Night	10% 10% 3 9% 5% 5% 6% 4 6% 7% 33%	2540
	11th to 20th	Night	12% 11% 4 9% 6% 6% 7% 5% 7% 9% 25%	2309
	21st to end	Night	13% 14% 5% 10% 6% 5% 5% 4 6% 6% 26%	2166
June	1st to 10th	Night	13% 9% 3 7% 6% 6% 8% 4 8% 7% 28%	1140
	11th to 20th	Night	15% 10% 3 9% 6% 5% 6% 5% 8% 7% 27%	1140
	21st to end	Night	10% 6% 3 9% 7% 7% 7% 5% 8% 8% 29%	1140
July	1st to 10th	Night	7% 6% 2 6% 4 5% 4 3 6% 7% 49%	1900
	11th to 20th	Night	7% 4 2 4 4 4 4 4 6% 7% 56%	2180
	21st to end	Night	14% 7% 2 6% 4 4 5% 4 7% 9% 38%	2414
August	1st to 10th	Night	4 3 1 3 3 2 3 2 5% 6% 68%	2424
	11th to 20th	Night	7% 5% 2 5% 4 5% 5% 4 6% 9% 48%	2560
	21st to end	Night	14% 8% 4 8% 5% 6% 5% 5% 6% 7% 34%	3146
September	1st to 10th	Night	12% 7% 3 7% 5% 5% 4 4 6% 8% 39%	1898
	11th to 20th	Night	10% 8% 3 6% 4 5% 5% 4 5% 8% 42%	1900
	21st to end	Night	16% 11% 4 8% 5% 4 5% 4 6% 6% 32%	2175
October	1st to 10th	Night	17% 14% 4 9% 6% 5% 5% 4 6% 7% 24%	3800
	11th to 20th	Night	12% 11% 4 9% 6% 6% 6% 4 7% 7% 28%	3797
	21st to end	Night	12% 12% 4 9% 5% 6% 6% 5% 5% 7% 28%	4696
November	1st to 10th	Night	17% 15% 4 7% 6% 6% 6% 5% 6% 5% 23%	2638
	11th to 20th	Night	12% 16% 5% 11% 8% 6% 5% 4 6% 6% 20%	2660
	21st to end	Night	12% 20% 5% 11% 6% 5% 6% 4 6% 6% 19%	2964
December	1st to 10th	Night	12% 16% 4 11% 7% 6% 6% 4 5% 5% 23%	3040
	11th to 20th	Night	18% 19% 5% 10% 7% 5% 5% 4 5% 6% 17%	3750
	21st to end	Night	8% 15% 5% 12% 8% 7% 6% 4 6% 6% 22%	5566

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	62% 14% 9% 12% 2	2063
	11th to 20th	Day	55% 8% 13% 10% 11% 4	2220
	21st to end	Day	67% 12% 11% 7% 3	2442
February	1st to 10th	Day	59% 9% 12% 10% 10%	1534
	11th to 20th	Day	58% 10% 14% 14% 5%	1674
	21st to end	Day	54% 9% 13% 14% 8% 2	1413
March	1st to 10th	Day	49% 10% 11% 18% 10%	3117
	11th to 20th	Day	46% 14% 17% 19% 4	3490
	21st to end	Day	42% 10% 16% 21% 11% 1	3973
April	1st to 10th	Day	54% 12% 12% 16% 6% 1	2280
	11th to 20th	Day	56% 8% 11% 19% 6%	2426
	21st to end	Day	52% 9% 14% 18% 8%	2649
May	1st to 10th	Day	41% 11% 20% 21% 6% 1	4420
	11th to 20th	Day	48% 13% 15% 16% 7% 1	4585
	21st to end	Day	52% 12% 14% 17% 4 1	5407
June	1st to 10th	Day	49% 12% 13% 18% 8%	3040
	11th to 20th	Day	50% 11% 16% 19% 4	3040
	21st to end	Day	45% 12% 17% 20% 6%	3040
July	1st to 10th	Day	30% 8% 12% 26% 23% 2	4981
	11th to 20th	Day	28% 7% 21% 31% 12%	4693
	21st to end	Day	38% 11% 18% 21% 11% 1	4976
August	1st to 10th	Day	21% 8% 20% 37% 13% 1	4488
	11th to 20th	Day	34% 9% 21% 28% 7%	4297
	21st to end	Day	47% 9% 25% 18% 2	4520
September	1st to 10th	Day	40% 11% 24% 21% 5%	2282
	11th to 20th	Day	41% 10% 19% 24% 5%	2280
	21st to end	Day	52% 11% 15% 17% 4 1	2003
October	1st to 10th	Day	56% 9% 19% 12% 5%	3180
	11th to 20th	Day	55% 9% 18% 16% 1	3140
	21st to end	Day	49% 11% 23% 11% 5%	2854
November	1st to 10th	Day	60% 9% 12% 13% 5%	1512
	11th to 20th	Day	64% 13% 10% 10% 4	1508
	21st to end	Day	67% 12% 10% 9% 2	1206
December	1st to 10th	Day	63% 11% 11% 12% 3	1140
	11th to 20th	Day	68% 11% 8% 8% 4	1444
	21st to end	Day	56% 10% 15% 13% 6%	2090
January	1st to 10th	Night	61% 13% 12% 12% 2	4910
	11th to 20th	Night	57% 7% 10% 7% 12% 6%	4740
	21st to end	Night	71% 10% 9% 7% 3	5214
February	1st to 10th	Night	63% 7% 12% 10% 8% 1	2644
	11th to 20th	Night	58% 9% 14% 14% 6%	2404
	21st to end	Night	52% 9% 13% 16% 8% 1	2041
March	1st to 10th	Night	50% 11% 11% 17% 9% 1	3754
	11th to 20th	Night	48% 12% 13% 21% 6%	3490
	21st to end	Night	37% 9% 13% 24% 17%	3679
April	1st to 10th	Night	52% 9% 13% 19% 7%	1900
	11th to 20th	Night	52% 8% 12% 19% 8%	1701
	21st to end	Night	50% 9% 11% 19% 11%	1530
May	1st to 10th	Night	44% 12% 15% 22% 7% 1	2540
	11th to 20th	Night	47% 14% 15% 18% 6%	2309
	21st to end	Night	55% 11% 11% 19% 4	2166
June	1st to 10th	Night	50% 11% 12% 17% 10%	1140
	11th to 20th	Night	52% 11% 12% 19% 6%	1140
	21st to end	Night	47% 11% 18% 19% 4	1140
July	1st to 10th	Night	32% 8% 11% 25% 23% 1	1870
	11th to 20th	Night	27% 7% 17% 39% 9%	2140
	21st to end	Night	38% 10% 21% 16% 13%	2337
August	1st to 10th	Night	18% 6% 17% 41% 18% 1	2417
	11th to 20th	Night	30% 8% 18% 34% 8%	2584
	21st to end	Night	48% 9% 24% 17% 3	3146
September	1st to 10th	Night	40% 9% 20% 24% 6% 1	1898
	11th to 20th	Night	39% 10% 14% 28% 8%	1900
	21st to end	Night	51% 9% 14% 18% 8%	2175
October	1st to 10th	Night	57% 8% 15% 16% 4	3800
	11th to 20th	Night	50% 9% 19% 18% 4	3797
	21st to end	Night	53% 10% 18% 15% 4	4696
November	1st to 10th	Night	60% 9% 13% 13% 5%	2638
	11th to 20th	Night	61% 10% 11% 13% 5%	2660
	21st to end	Night	62% 11% 12% 11% 3	2964
December	1st to 10th	Night	59% 11% 12% 14% 5%	3040
	11th to 20th	Night	67% 11% 10% 8% 4	3747
	21st to end	Night	56% 12% 14% 13% 5%	5566

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	16% 8% 22% 32% 16% 7%	180
	11th to 20th	Day	21% 13% 19% 26% 17% 4	180
	21st to end	Day	24% 13% 23% 21% 15% 4	198
February	1st to 10th	Day	23% 20% 25% 16% 12% 3	226
	11th to 20th	Day	19% 12% 26% 24% 16% 3	365
	21st to end	Day	13% 17% 31% 23% 11% 5%	307
March	1st to 10th	Day	14% 17% 24% 23% 17% 6%	447
	11th to 20th	Day	17% 15% 28% 21% 16% 3	460
	21st to end	Day	18% 17% 24% 18% 16% 7%	506
April	1st to 10th	Day	15% 16% 27% 27% 12% 3	460
	11th to 20th	Day	16% 14% 27% 23% 14% 6%	452
	21st to end	Day	16% 15% 28% 25% 12% 3	460
May	1st to 10th	Day	16% 15% 27% 24% 15% 3	463
	11th to 20th	Day	12% 10% 24% 30% 20% 5%	600
	21st to end	Day	14% 7% 23% 27% 24% 5%	876
June	1st to 10th	Day	15% 9% 25% 29% 19% 3	870
	11th to 20th	Day	16% 8% 23% 28% 20% 5%	870
	21st to end	Day	12% 6% 25% 29% 24% 6%	870
July	1st to 10th	Day	15% 5% 17% 30% 24% 8%	856
	11th to 20th	Day	16% 6% 18% 26% 27% 7%	689
	21st to end	Day	10% 7% 18% 29% 28% 8%	739
August	1st to 10th	Day	9% 6% 16% 30% 28% 11%	554
	11th to 20th	Day	9% 5% 25% 29% 21% 10%	477
	21st to end	Day	14% 8% 28% 26% 17% 7%	539
September	1st to 10th	Day	15% 8% 24% 23% 24% 6%	490
	11th to 20th	Day	15% 8% 21% 26% 23% 7%	490
	21st to end	Day	20% 14% 29% 20% 13% 4	490
October	1st to 10th	Day	22% 12% 22% 23% 15% 6%	490
	11th to 20th	Day	22% 11% 26% 22% 16% 3	481
	21st to end	Day	20% 13% 26% 25% 13% 3	253
November	1st to 10th	Day	35% 10% 22% 20% 8% 5%	186
	11th to 20th	Day	23% 11% 23% 19% 18% 6%	180
	21st to end	Day	26% 10% 24% 26% 11% 3	180
December	1st to 10th	Day	17% 7% 21% 28% 21% 6%	180
	11th to 20th	Day	13% 10% 19% 33% 20% 4	180
	21st to end	Day	23% 7% 15% 34% 16% 6%	198
January	1st to 10th	Night	24% 9% 24% 29% 11% 3	956
	11th to 20th	Night	24% 9% 25% 26% 15% 1	850
	21st to end	Night	24% 13% 23% 26% 12% 2	935
February	1st to 10th	Night	26% 13% 17% 26% 15% 2	774
	11th to 20th	Night	20% 9% 22% 31% 16% 1	744
	21st to end	Night	18% 10% 21% 32% 16% 3	628
March	1st to 10th	Night	18% 11% 23% 30% 16% 3	760
	11th to 20th	Night	16% 12% 24% 32% 15% 1	760
	21st to end	Night	15% 9% 17% 29% 25% 5%	836
April	1st to 10th	Night	18% 8% 20% 30% 21% 3	760
	11th to 20th	Night	15% 6% 23% 32% 19% 5%	573
	21st to end	Night	17% 7% 25% 30% 20% 2	390
May	1st to 10th	Night	16% 7% 22% 34% 17% 4	380
	11th to 20th	Night	13% 3 18% 37% 26% 3	374
	21st to end	Night	15% 6% 21% 31% 26% 2	411
June	1st to 10th	Night	17% 5% 21% 35% 20% 3	380
	11th to 20th	Night	19% 4 23% 27% 24% 4	380
	21st to end	Night	12% 5% 17% 34% 30% 2	380
July	1st to 10th	Night	13% 2 15% 37% 31% 1	370
	11th to 20th	Night	13% 3 15% 35% 30% 4	368
	21st to end	Night	13% 4 12% 35% 31% 6%	416
August	1st to 10th	Night	8% 3 10% 32% 38% 8%	378
	11th to 20th	Night	9% 2 15% 36% 32% 6%	413
	21st to end	Night	20% 4 13% 33% 27% 4	627
September	1st to 10th	Night	17% 4 15% 34% 27% 3	758
	11th to 20th	Night	14% 5% 13% 32% 30% 6%	760
	21st to end	Night	21% 10% 21% 28% 17% 2	760
October	1st to 10th	Night	21% 8% 17% 31% 19% 4	760
	11th to 20th	Night	22% 7% 24% 29% 17% 2	760
	21st to end	Night	24% 11% 24% 30% 11%	836
November	1st to 10th	Night	27% 12% 20% 29% 10% 2	754
	11th to 20th	Night	24% 13% 24% 27% 10% 1	760
	21st to end	Night	26% 12% 23% 28% 8% 2	999
December	1st to 10th	Night	20% 8% 19% 34% 18% 2	1040
	11th to 20th	Night	25% 9% 20% 31% 13% 2	1040
	21st to end	Night	20% 9% 24% 30% 14% 2	1144

Page generated at 2024-11-01 19:47:38. Version ac07

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