Ucluelet
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ucluelet clear sky chart from 2005-11-06 to 2024-09-14.

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	26% 10% 3 7% 4 4 4 3 5% 6% 27%	101220
	Night	31% 11% 3 7% 4 3 3 3 4 5% 27%	96771
Transparency	Day	56% 7% 13% 15% 7% 1	100962
	Night	60% 6% 11% 15% 7% 1	96676
Seeing	Day	28% 5% 13% 24% 22% 8%	15617
	Night	36% 5% 12% 21% 18% 8%	23527

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	44% 12% 2 5% 3 3 3 3 4 4 16%	2219
	11th to 20th	Day	35% 11% 3 7% 4 4 4 3 4 5% 20%	2199
	21st to end	Day	57% 10% 3 7% 3 2 2 2 2 2 11%	2765
February	1st to 10th	Day	40% 13% 3 6% 4 4 4 3 4 5% 15%	1710
	11th to 20th	Day	36% 10% 3 7% 5% 3 2 2 3 4 25%	1665
	21st to end	Day	31% 11% 3 8% 4 4 2 2 4 6% 24%	1413
March	1st to 10th	Day	29% 12% 3 8% 5% 5% 4 4 5% 6% 19%	3314
	11th to 20th	Day	30% 8% 3 7% 5% 4 4 2 5% 4 28%	3490
	21st to end	Day	31% 11% 4 7% 5% 4 4 3 4 5% 22%	3825
April	1st to 10th	Day	34% 12% 3 7% 4 3 4 3 4 6% 21%	2275
	11th to 20th	Day	27% 11% 3 6% 4 4 3 4 4 6% 26%	2438
	21st to end	Day	30% 9% 3 7% 4 4 4 3 4 6% 26%	2470
May	1st to 10th	Day	22% 8% 2 6% 4 4 4 3 4 6% 37%	4317
	11th to 20th	Day	16% 10% 3 7% 4 4 5% 4 7% 9% 31%	4377
	21st to end	Day	24% 11% 3 9% 5% 4 5% 4 6% 6% 24%	5154
June	1st to 10th	Day	26% 11% 4 7% 4 5% 4 3 6% 6% 24%	2850
	11th to 20th	Day	19% 12% 4 9% 6% 5% 5% 4 6% 8% 22%	2850
	21st to end	Day	23% 11% 4 6% 4 4 5% 3 5% 6% 28%	2850
July	1st to 10th	Day	11% 7% 3 5% 3 3 4 4 6% 8% 46%	4740
	11th to 20th	Day	9% 8% 3 6% 5% 5% 6% 5% 7% 9% 37%	4740
	21st to end	Day	17% 10% 3 7% 4 4 5% 4 6% 8% 33%	5107
August	1st to 10th	Day	9% 8% 4 9% 6% 6% 8% 7% 9% 11% 24%	4107
	11th to 20th	Day	16% 14% 4 11% 6% 5% 5% 4 6% 7% 22%	4026
	21st to end	Day	19% 8% 3 7% 4 4 3 3 5% 7% 37%	4521
September	1st to 10th	Day	17% 9% 3 7% 5% 4 4 4 5% 8% 34%	2312
	11th to 20th	Day	23% 9% 3 7% 4 3 5% 4 5% 5% 31%	2067
	21st to end	Day	26% 7% 2 6% 3 3 4 3 4 5% 37%	1980
October	1st to 10th	Day	27% 7% 3 7% 4 4 5% 3 6% 6% 29%	1800
	11th to 20th	Day	33% 10% 3 5% 5% 4 4 4 7% 6% 19%	1800
	21st to end	Day	36% 8% 2 6% 3 2 4 3 4 5% 27%	1834
November	1st to 10th	Day	42% 8% 2 7% 4 3 3 4 5% 3 18%	1488
	11th to 20th	Day	42% 10% 3 6% 3 2 3 2 3 3 22%	1520
	21st to end	Day	40% 8% 2 5% 3 4 4 2 3 5% 22%	1520
December	1st to 10th	Day	32% 12% 2 6% 4 3 4 3 2 5% 27%	1350
	11th to 20th	Day	44% 11% 3 6% 4 3 3 3 3 3 17%	1685
	21st to end	Day	51% 10% 3 6% 4 3 2 3 3 4 12%	2442
January	1st to 10th	Night	42% 14% 3 8% 4 3 3 3 3 3 15%	4726
	11th to 20th	Night	37% 10% 3 6% 3 3 3 3 4 5% 25%	4699
	21st to end	Night	60% 10% 2 5% 2 2 2 2 2 2 10%	4894
February	1st to 10th	Night	41% 12% 2 5% 4 3 3 3 4 5% 19%	2470
	11th to 20th	Night	32% 12% 2 6% 4 3 3 2 4 5% 27%	2402
	21st to end	Night	34% 12% 3 8% 4 3 3 2 4 4 24%	2041
March	1st to 10th	Night	31% 12% 3 7% 5% 4 4 3 4 5% 22%	3553
	11th to 20th	Night	26% 12% 3 8% 6% 3 4 3 5% 4 25%	3489
	21st to end	Night	34% 16% 4 8% 4 3 3 2 3 3 21%	3828
April	1st to 10th	Night	33% 12% 3 7% 4 4 3 3 4 4 23%	1902
	11th to 20th	Night	28% 13% 2 6% 5% 3 4 3 5% 5% 27%	1691
	21st to end	Night	30% 11% 3 7% 5% 4 4 2 3 4 26%	1710
May	1st to 10th	Night	19% 8% 2 5% 3 4 3 2 5% 6% 43%	2646
	11th to 20th	Night	14% 11% 3 7% 5% 4 4 3 4 7% 40%	2516
	21st to end	Night	27% 10% 3 7% 4 3 4 3 5% 6% 29%	2418
June	1st to 10th	Night	26% 12% 2 7% 5% 4 4 3 4 5% 27%	1330
	11th to 20th	Night	23% 11% 4 8% 5% 5% 4 3 4 5% 28%	1330
	21st to end	Night	19% 12% 5% 8% 5% 3 5% 4 5% 7% 29%	1330
July	1st to 10th	Night	10% 8% 2 4 3 3 3 3 5% 8% 53%	2220
	11th to 20th	Night	7% 10% 2 6% 3 3 3 3 5% 7% 50%	2220
	21st to end	Night	16% 12% 3 7% 4 3 4 3 5% 5% 38%	2444
August	1st to 10th	Night	7% 9% 4 9% 5% 5% 5% 4 6% 8% 37%	2830
	11th to 20th	Night	18% 16% 4 8% 5% 4 4 3 4 5% 29%	2812
	21st to end	Night	16% 10% 3 6% 4 4 3 3 4 6% 41%	3146
September	1st to 10th	Night	12% 10% 2 6% 4 3 4 3 5% 6% 45%	1867
	11th to 20th	Night	23% 10% 3 6% 4 4 3 3 4 6% 34%	1970
	21st to end	Night	27% 7% 2 4 3 4 3 2 5% 5% 37%	1980
October	1st to 10th	Night	26% 8% 3 7% 4 3 4 3 4 4 35%	2160
	11th to 20th	Night	34% 9% 2 7% 4 3 4 2 4 5% 26%	2160
	21st to end	Night	36% 7% 2 7% 4 3 3 2 3 4 29%	2517
November	1st to 10th	Night	42% 10% 2 6% 4 4 3 3 3 4 18%	2590
	11th to 20th	Night	37% 10% 3 8% 5% 4 4 3 3 3 20%	2660
	21st to end	Night	40% 9% 2 6% 4 4 3 2 4 4 23%	2660
December	1st to 10th	Night	32% 12% 3 6% 4 4 4 3 4 4 24%	2826
	11th to 20th	Night	46% 11% 2 7% 4 3 3 2 3 4 15%	3520
	21st to end	Night	48% 12% 3 7% 3 3 3 2 3 3 14%	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	72% 5% 8% 10% 5% 1	2219
	11th to 20th	Day	63% 8% 8% 14% 5% 1	2220
	21st to end	Day	83% 3 4 8% 2	2765
February	1st to 10th	Day	71% 7% 7% 9% 5% 1	1710
	11th to 20th	Day	65% 4 8% 13% 8% 1	1674
	21st to end	Day	63% 4 9% 14% 8% 2	1413
March	1st to 10th	Day	62% 7% 12% 12% 7% 1	3314
	11th to 20th	Day	58% 6% 10% 20% 6% 1	3490
	21st to end	Day	64% 8% 15% 11% 2	3825
April	1st to 10th	Day	65% 7% 11% 12% 5% 1	2275
	11th to 20th	Day	58% 6% 11% 14% 9% 1	2438
	21st to end	Day	59% 6% 12% 15% 6% 1	2470
May	1st to 10th	Day	49% 6% 16% 22% 7%	4317
	11th to 20th	Day	47% 13% 17% 19% 4	4380
	21st to end	Day	59% 8% 16% 11% 5% 1	5155
June	1st to 10th	Day	59% 9% 15% 11% 5% 1	2850
	11th to 20th	Day	58% 10% 16% 12% 4	2850
	21st to end	Day	55% 10% 15% 13% 6% 1	2850
July	1st to 10th	Day	33% 6% 12% 21% 19% 9%	4666
	11th to 20th	Day	38% 7% 16% 26% 13%	4659
	21st to end	Day	47% 8% 17% 18% 9% 1	4946
August	1st to 10th	Day	46% 9% 13% 24% 7% 1	4090
	11th to 20th	Day	60% 7% 17% 9% 6% 1	4065
	21st to end	Day	46% 7% 17% 22% 8%	4520
September	1st to 10th	Day	46% 11% 13% 19% 9% 3	2312
	11th to 20th	Day	55% 9% 10% 13% 11% 1	2067
	21st to end	Day	50% 7% 14% 19% 8% 2	1980
October	1st to 10th	Day	53% 9% 13% 12% 11% 2	1800
	11th to 20th	Day	62% 7% 13% 13% 4	1800
	21st to end	Day	60% 5% 11% 14% 9% 1	1834
November	1st to 10th	Day	69% 5% 12% 9% 4 1	1488
	11th to 20th	Day	68% 5% 8% 10% 8% 1	1520
	21st to end	Day	66% 5% 7% 14% 7% 1	1520
December	1st to 10th	Day	63% 5% 11% 13% 6% 2	1350
	11th to 20th	Day	73% 5% 7% 9% 4 1	1688
	21st to end	Day	77% 6% 6% 7% 4 1	2442
January	1st to 10th	Night	75% 6% 5% 10% 4 1	4726
	11th to 20th	Night	61% 4 9% 18% 6% 1	4740
	21st to end	Night	83% 3 4 8% 2 1	4894
February	1st to 10th	Night	70% 6% 8% 9% 6% 1	2470
	11th to 20th	Night	60% 6% 9% 13% 10% 1	2404
	21st to end	Night	65% 5% 7% 15% 7% 1	2041
March	1st to 10th	Night	62% 7% 10% 14% 6% 1	3553
	11th to 20th	Night	59% 8% 9% 17% 7% 1	3490
	21st to end	Night	70% 6% 10% 11% 2	3828
April	1st to 10th	Night	64% 6% 10% 13% 6%	1902
	11th to 20th	Night	59% 5% 9% 17% 7% 2	1691
	21st to end	Night	62% 6% 8% 16% 8% 1	1710
May	1st to 10th	Night	43% 7% 20% 21% 9%	2646
	11th to 20th	Night	44% 8% 22% 18% 7% 1	2516
	21st to end	Night	55% 10% 13% 17% 4 1	2418
June	1st to 10th	Night	60% 6% 15% 12% 5% 2	1330
	11th to 20th	Night	58% 8% 17% 13% 4 1	1330
	21st to end	Night	53% 9% 14% 15% 7% 1	1330
July	1st to 10th	Night	31% 6% 11% 22% 20% 11%	2185
	11th to 20th	Night	30% 7% 14% 35% 12% 2	2178
	21st to end	Night	42% 10% 17% 22% 8% 1	2367
August	1st to 10th	Night	42% 6% 17% 25% 10% 1	2822
	11th to 20th	Night	57% 5% 17% 12% 6% 2	2839
	21st to end	Night	45% 6% 18% 22% 9%	3146
September	1st to 10th	Night	40% 7% 13% 26% 10% 3	1867
	11th to 20th	Night	53% 7% 11% 13% 13% 2	1970
	21st to end	Night	49% 7% 14% 17% 10% 3	1980
October	1st to 10th	Night	52% 6% 11% 17% 13% 1	2160
	11th to 20th	Night	62% 5% 13% 13% 7%	2160
	21st to end	Night	62% 6% 9% 15% 8%	2517
November	1st to 10th	Night	70% 5% 9% 10% 5% 1	2590
	11th to 20th	Night	70% 6% 8% 8% 6% 2	2660
	21st to end	Night	65% 5% 10% 11% 7% 2	2660
December	1st to 10th	Night	65% 6% 9% 12% 7% 2	2826
	11th to 20th	Night	75% 5% 8% 6% 5% 1	3516
	21st to end	Night	77% 5% 7% 7% 4 1	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	48% 8% 19% 15% 8% 2	180
	11th to 20th	Day	47% 7% 17% 20% 9% 1	180
	21st to end	Day	50% 5% 10% 17% 14% 3	350
February	1st to 10th	Day	43% 10% 15% 21% 10% 2	370
	11th to 20th	Day	39% 6% 16% 25% 12% 2	365
	21st to end	Day	34% 12% 16% 24% 10% 3	307
March	1st to 10th	Day	33% 7% 15% 20% 22% 4	424
	11th to 20th	Day	36% 7% 14% 22% 17% 4	460
	21st to end	Day	39% 6% 13% 23% 15% 4	506
April	1st to 10th	Day	38% 8% 16% 21% 13% 4	460
	11th to 20th	Day	30% 4 15% 28% 14% 9%	452
	21st to end	Day	32% 8% 16% 27% 14% 4	460
May	1st to 10th	Day	23% 4 15% 27% 26% 5%	463
	11th to 20th	Day	24% 5% 12% 25% 24% 10%	488
	21st to end	Day	20% 5% 16% 29% 23% 7%	728
June	1st to 10th	Day	30% 5% 14% 25% 22% 5%	680
	11th to 20th	Day	19% 6% 18% 31% 21% 5%	680
	21st to end	Day	22% 4 12% 26% 25% 11%	680
July	1st to 10th	Day	18% 4 10% 25% 34% 9%	671
	11th to 20th	Day	15% 2 11% 26% 33% 13%	668
	21st to end	Day	11% 3 10% 25% 37% 15%	720
August	1st to 10th	Day	16% 2 8% 19% 32% 22%	487
	11th to 20th	Day	15% 4 8% 18% 34% 20%	477
	21st to end	Day	21% 4 9% 26% 27% 13%	539
September	1st to 10th	Day	22% 3 9% 24% 31% 11%	490
	11th to 20th	Day	27% 3 11% 22% 24% 13%	463
	21st to end	Day	29% 2 14% 24% 21% 10%	450
October	1st to 10th	Day	29% 5% 9% 24% 23% 10%	450
	11th to 20th	Day	36% 7% 10% 20% 19% 8%	450
	21st to end	Day	38% 8% 14% 20% 13% 7%	421
November	1st to 10th	Day	43% 7% 14% 19% 15% 2	180
	11th to 20th	Day	38% 7% 14% 18% 15% 8%	180
	21st to end	Day	41% 8% 21% 12% 12% 6%	180
December	1st to 10th	Day	39% 7% 14% 20% 13% 6%	180
	11th to 20th	Day	41% 8% 17% 20% 11% 3	180
	21st to end	Day	47% 8% 12% 21% 11% 1	198
January	1st to 10th	Night	52% 8% 15% 16% 7% 1	850
	11th to 20th	Night	47% 7% 10% 21% 13% 1	850
	21st to end	Night	49% 5% 12% 17% 13% 3	915
February	1st to 10th	Night	46% 6% 16% 21% 9% 1	760
	11th to 20th	Night	38% 7% 15% 26% 13% 1	744
	21st to end	Night	40% 9% 16% 23% 8% 3	628
March	1st to 10th	Night	37% 9% 13% 18% 18% 5%	760
	11th to 20th	Night	40% 8% 15% 19% 13% 4	760
	21st to end	Night	41% 7% 13% 19% 16% 4	836
April	1st to 10th	Night	39% 6% 11% 22% 16% 6%	727
	11th to 20th	Night	34% 6% 10% 25% 20% 6%	563
	21st to end	Night	33% 6% 16% 23% 18% 4	570
May	1st to 10th	Night	24% 5% 9% 23% 28% 10%	447
	11th to 20th	Night	28% 4 7% 21% 29% 11%	374
	21st to end	Night	25% 2 11% 26% 27% 9%	411
June	1st to 10th	Night	29% 4 8% 24% 24% 10%	380
	11th to 20th	Night	24% 4 14% 28% 22% 7%	380
	21st to end	Night	21% 4 8% 26% 28% 13%	380
July	1st to 10th	Night	19% 3 6% 17% 38% 16%	370
	11th to 20th	Night	14% 4 7% 20% 35% 21%	368
	21st to end	Night	14% 2 8% 16% 32% 28%	416
August	1st to 10th	Night	21% 1 5% 13% 29% 30%	549
	11th to 20th	Night	17% 1 4 12% 37% 29%	564
	21st to end	Night	25% 1 10% 19% 30% 14%	627
September	1st to 10th	Night	19% 2 6% 22% 32% 18%	727
	11th to 20th	Night	28% 3 10% 14% 26% 19%	736
	21st to end	Night	32% 2 11% 22% 22% 11%	720
October	1st to 10th	Night	31% 4 9% 23% 23% 11%	720
	11th to 20th	Night	39% 3 9% 19% 21% 8%	720
	21st to end	Night	41% 5% 15% 23% 12% 4	792
November	1st to 10th	Night	46% 5% 17% 22% 9% 1	740
	11th to 20th	Night	44% 8% 14% 20% 10% 3	760
	21st to end	Night	43% 6% 14% 21% 11% 4	760
December	1st to 10th	Night	37% 6% 15% 24% 15% 3	838
	11th to 20th	Night	48% 7% 15% 20% 9% 1	850
	21st to end	Night	48% 7% 17% 22% 5% 1	935

Page generated at 2024-09-11 07:00:02. Version ac07

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